No. 1246.

JULY 17, 1847.

A Course of LecturesON

THE PHYSICAL PHENOMENAOF

LIVING BODIES.

DELIVERED IN THE UNIVERSITY OF PISA.

BY PROFESSOR MATTEUCCI, F.R.S.(Translated, for THE LANCET, by S. J. GOODFELLOW, M.D. Lond.,

late Physician to the Cumberland Infirmary.)

· LECTURE VII.

;S’<mg’Mt/K;<t<M’M.&mdash;MtfOM.&mdash;4 Ma! Heat.

IN the last lecture, I showed that during respiration a por-tion of the oxygen of the inspired air disappears, and that inits place is formed an equal or smaller quantity of carbonicacid; that the expired air is saturated with aqueous vapour,and that at the same time that these changes are effected inthe lungs, the venous blood is converted into arterial. Wehave also seen that all these phenomena take place as well outoi the living body, and under the same conditions, as whenthey are carried on within it. It remains to examine the par-ticulars of this change in the blood. Which of the organicelements of the blood undergoes this change, and in what doesit chemically consist ? 1 If I must give a direct answer to thesequestions, I must confess that, up to the present time, the ex-periments tried in order to resolve them have afforded butlittle information, and among the immense number of attemptsthat have been made, I can only choose those which appear tobe on the whole the least imperfect and contradictory. Micro-scopical observers of the present day define the blood as aliquid chiefly composed of water, in which are dissolved dif-ferent salts, albumen, fibrine, and oily particles, and whichholds in suspension a great number of red globules, of a regular iform, and greater or less diameter, according to the differentspecies of animals, and resembling a kind of vesicle with acoloured envelope soluble in acetic acid. I wish to show youa beautiful experiment of Muller’s, which will give you a cor-rect idea of this composition of the blood.

I pierce the hearts of several frogs, and receive the bloodthat flows from them upon a paper filter; a yellowish liquidescapes through the filter, and the red globules remain uponit. In a few seconds you will see the filtered liquid coagulate,and the clot will be composed of fibrine. Thus we have, onthe one hand, the colouring matter, and on the other, theserum in which fibrine is dissolved. If the blood had notbeen filtered, the fibrine would equally have coagulated, butwould have enclosed the globular matter; and this is whattakes place in blood out of the living body. According tocircumstances purely physical, as the temperature of theblood when drawn, the density of the serum, the differentproportions of globules and fibrine, so does the coagulation ofthe blood take place more or less quickly, is more or lessabundant, and the coagulum formed offers greater or less re-sli.it.n.nce-

When we take only the coagulum which is formed in a massof blood left to itself, and treat it with oxygen, we see it assumea red colour. This coagulum exposed to the air, and then cut,has a blackish colour inside, and a red colour outside. Thefresh surfaces formed by the incision, when exposed to theair, soon become red. It is undoubtedly the globules of bloodwhich undergo this change of colour by contact with the air.Baudrimont and Martin Saint-Ange have lately shown, thatduring the period of incubation, the absorption of oxygenand exhalation of carbonic acid are carried oh through thecalcareous envelope of the egg; and they have proved that ifthese processes are prevented, the red globules are not de-veloped in the embryo. It still remains to be proved whetherthe globules become red merely by absorbing oxygen, or bylosing carbonic acid during respiration; or if, on the contrary,the blood becomes venous on account of the greater quantityof carbonic acid with which it is charged, or by reason of thesmaller quantity of oxygen which remains in it, or if it be theeffect of both these circumstances combined. Exact experi-ments on this point are wanting. Magnus has proved thatvenous blood, by losing the greatest possible quantity of car-bonic acid, becomes less dark, but without acquiring a ver-million colour. This fact would lead us to suppose that thetwo causes simultaneously effect the change of colour which

the blood undergoes during respiration. I must add, that ifall the serum be carefully separated from the coagulum, andthe latter be then washed with distilled water, to take awayall trace of the serum, in this condition it will no loggerassume that beautiful red colour which it acquires by contactwith oxygen when it is immersed in serum.* Here is asaturated solution of bay salt, which I pour drop by dropupon the coagulum of the blood. You see that the pointsupon which it falls acquire a red colour, while the remainderof the surface does not change. It would appear from this,that the salts of the serum are concerned in the modificationwhich the colour of the blood undergoes when oxygen ispresent. It is now known that the serum absorbs a muchlarger quantity of carbonic acid than can be dissolved bywater. It may therefore be said that the presence of seruminfluences the change of colour in the blood, by becomingcharged with a portion of carbonic acid, of which it is after-WOTft’.! rlanrivarl hv the oxygen

But in what does this change of colour of the blood-globuleschemically consist? With regard to this question, Scienceis still in the dark. The great quantity of iron (five or sixper cent.) which always exists in the blood-globules, andwhich is not found in so large a proportion in any otheranimal substance, has led to the supposition that this metal,which is sometimes found as peroxide, and sometimes as acarbonate, cannot but influence the change of colour in theblood. In fact, the oxygen expels the carbonic acid from thecarbonate of iron, and the carbonic acid, in its turn, replacesthe oxygen of the peroxide, according to the relative propor-tions of oxygen and carbonic acid which are at liberty to actupon the oxide of iron.Mulder and Liebig seem to have embraced these opinions.

All the best supported clinical results seem to prove that theuse of iron in certain maladies in some degree revives thecolour of the blood. Nevertheless, Scherer has lately assertedthat he has obtained the colouring matter of the blood, en-tirely devoid of iron. If this observation of Scherer’s be ulti-mately confirmed, and if it be also proved that this colouringmatter, deprived of iron, undergoes by contact with oxygenand carbonic acid the changes that we have seen take placein the blood-globules, we shall be obliged to renounce theopinion, that iron is instrumental in changing the colour ofthe blood.tThe arterial blood, propelled by the unceasing contractions

of the heart, as well as by the successive distentions and con-tractions of the arteries, owing to their peculiar elasticity,reaches the smallest capillaries with this red colour. Alwayscirculating in them, it passes through all the tissues, loses itsred colour, and returns by the veins to the heart, to be againsubjected to the action of the lungs. It is during this passageof the arterial blood through the capillaries, that nutrition issaid by physiologists to take place. In this science, it isadmitted that all parts of the animal tissues are constantlyrenewed and transformed, and that these phenomena vary in.intensity, and are proportional to the different degrees ofactivity in the capillary system peculiar to the various tissues.To speak the truth, the experimental proofs of this continualrenovation are wanting, and that which is afforded by thecolouring of the bony parts of animals fed upon colouredsubstances, and by their losing this colour on their food beingchanged, has always appeared to me insufficient. It must,however, be confessed, that this renovatiop is proved by theaccumulated evidence of physiological facts. Were I tomention here all the experimental deductions which arewanting, and which would be necessary to explain the act ofnutrition, I should occupy a much longer time than we canat present bestow on this subject. The blood-globules, notforming a part of any tissue, but still being essential to nutri-tion, may be regarded, with some probability, as the catalytic* This is a very unsatisfactory experiment; for, by washing-the coagulum

with distilled water, it would necessarily be deprived of a good deal of itscolouring matter, and nearly all the red particles would be destroyed, ormore or less injured. It would be quite as difficult to separate the serumfrom the red particles by this process of ablution, as to prevent their sepa-ration from the fibrme of the clot.

t It may not be out of place here to allude to the views upon this subjectlately promulgated by Dr. G. 0. Rees. According to this ingenious ob-server and able chemist, the venous corpuscles contain a fatty matter, incombination with phosphorus, which, on coming into contact with theoxygen of the atmosphere, during the respiratory act, is consumed, andcombining with that oxygen, forms carbonic acid and water, which areexpired, and also phosphoric acid, which, uniting with the alkali of theliquor sanguinis, forms a tribasic phosphate of soda. This salt, it appears,has the property of acting upon hsematosine, so as to produce the brightarterial tint. That this tint is probably owing to this salt in solution inthe serum, is rendered likely, by the fact, that it is found in much greaterquantity in the serum of arterial than in that of venous blood.-TRANS.

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body, which excites or sets in action the transformation oftissues, and their constant renovation. An analogy of thischaracter of the globules is made apparent in the necessitywhich exists for their being charged with oxygen, in order toacquire this property.

It may also be remarked, that as in vegetables the diastasechanges starch into dextrine, which is again transformed intocellulose and lignine-that is to say, into isomeric substances,so, in the same way, may the blood-globules convert albumeninto fibrine; and this change certainly takes place in theembryo. ,

I wish I could say that experiment had shown the reality ’,of these changes, as in the case of starch. I have made manyattempts with this end; but the results I have obtained still ’Ileave me in doubt. I kept some albumen of an egg, mixed with a small quantity of the blood-globules of a fowl, exposedto oxygen for a month, at a constant temperature of 104&deg;Fahr. A receiver, into which flowed hot mineral water,afforded a medium of an unvarying degree of heat. I sawthat the oxygen partly disappeared, that it was replaced bycarbonic acid, and that a great number of reddish flakes weredeposited at the bottom of the receiver; yet the originalliquid was limpid, and scarcely coloured. These flakes, whenexamined, did not appear to be identical with fibrine. Never-theless, I would not conclude from these negative resultsthat the principle on which my experiments were foundedwas false. This is a subject which requires longer and morevaried researches.To return, however, to our original subject. During the

act of nutrition, one part of the arterial blood disappears, andis replaced by an excess of carbonic acid in the venous blood.The oxygen combines with the carbon in the capillary vessels.It is certainly in them that this combination takes place; andsince we find that the volume of carbonic acid expired is notsufficient to account for the oxygen which has disappearedduring respiration, we must admit that not only the carbonunites with the oxygen to form carbonic acid, but that thehydrogen, which forms a part of the organic elements of thebiood and tissues, also combines with the oxygen to formwater. Here then is another instance of combustion besidesthat of carbon.The acetates, tartrates, and oxalates, which enter the blood

in a state of solution, are expelled by the urinary passages inthe form of carbonates. Benzoic acid, introduced into thecirculation, escapes, in the state of hippuric acid, by the samepassages. In concert with Professor Piria, I have tried intro-ducing a solution of salicine into the blood of a living animal.After some time, a substance, derived from salicine, was dis-covered in the urine, which had the property of forming aviolet precipitate with salts of iron.An important observation, recently made by Dessains,

deserves our notice. By boiling hippuric acid in a solutionof hydrochloric acid, benzoic acid was precipitated, and weobtained a solution of hydrochloric acid, combined with asweet azotised substance, which is the sugar of gelatine ofBraconnot. It is known that this substance is obtained bytreating neutral azotised matters, as proteine and gelatine,with acids. It is also known that hippuric acid in herbivorousanimals is the substitute for the urea in the carnivorous. Wediscover from this that the sugar of gelatine is one of the firstproducts of the transformation of those neutral azotised sub-stances which are the materials of our tissues. We mayalso understand how, by adding benzoic acid, which combineswith those substances, hippuric acid is obtained.

All these facts place it beyond doubt, that the chief che-mical action observed in the circulation of the blood, and innutrition, is a kind of combustion; that it is a combination ofoxygen with carbon and hydrogen. Yet, I repeat, there iseven now great obscurity in our knowledge of the order ofthese phenomena. What is the difference, in chemical com-position, between arterial and venous blood ? What is thenature of this difference in the blood before and after its pas-sage through the kidneys, the liver, and the various tissues?These are some of the numerous questions which ought to beresolved by exact experiments, and by researches, all agree-ing in their results, before prosecuting our investigations uponthe phenomena of nutrition and secretion.As we have seen, the aliments pass into the blood after

having undergone various modifications by the act of diges-tion. But many of these, in their natural state, are identicalwith the organic elements of the animal tissues, as, for ex-ample, the neutral azotised substances, and also fatty sub-stances, which are found in the adipose tissues, scarcely, if atall altered. It would be unreasonable and absurd to admitBhat urea, carbonic acid, and water, which are the definite pro-

ducts of the transformations effected by nutrition, are fur.nished from those organic elements which have been intro.duced into the blood with the food. We must believe thatthese products result from the transformations of the tissuesthemselves, and are replaced by new organic elements de.rived from the food. In fact, the production of urea takesplace in animals fed for a long time upon sugar, starch, or gum,just the same as before the use of such a diet. The same

thing has been remarked in animals that have died from inani-tion.For the sake of rendering this more apparent, I will cite to

you some examples from the work of Liebig, on "OrganicChemistry applied to Animal Physiology."A serpent kept for some time without food, and then

allowed to feed on a goat, rabbit, or fowl, passes in its excre.ments the hair and bones of the animal devoured, exhalescarbonic acid and water, and discharges by the urinarypassages only urate of ammonia. It afterwards regained itsusual weight, and no trace remained of the animal it had de.voured. Let us analyze this simple case of nutrition. Theurate of ammonia contains one equivalent of nitrogen to twoof carbon; the muscles and blood of the animal eaten con-tained eight equivalents of carbon to one of nitrogen, and if tothis we add the carbon of the fat and brain of the devouredanimal, it will be apparent that the serpent consumed morethan eight equivalents of carbon to one of nitrogen. In theexcrements, only two equivalents of carbon are found; the sixequivalents which are wanting must have been expelled in theform of carbonic acid. It is unnecessary for me to repeat thatthe urate of ammonia and the carbonic acid are derived fromthe transformed tissues, and their place supplied by theorganic elements (proximate principles) of the animal digested.It is universally true, that as much carbon and azote are foundin the products generated by the transformation of the tissuesfrom their contact with arterial blood, as the tissues them-selves derive from the blood or food. What I have just saidof the serpent equally applies to the lion and other carnivorousanimals. In their urine there is urea only, in which the pro-portion of nitrogen to carbon is as two to one; and, as in thefood of these animals the nitrogen is to the carbon as one is toeight, it follows that the excess of carbon introduced with thefood over that carried off by the urine, disappears in respira-tion, is, in fact, burnt and converted into carbonic acid. Therespiration of the lion is, however, much more active thanthat of the serpent.The fifteen (232 grains) or twenty grammes (310 grains)

of nitrogen which a man loses every day in the urine, as wellas the excess of nitrogen which he expires, are furnished bythe neutral azotised substances of his food, or, more directly,by the transformed tissues which are replaced by those ali-mentary substances.

Boussingault proved, by experiment, that the whole of thenitrogen contained in a horse’s food is not found in his urine,and thus demonstrated that the excess of nitrogen expired isalso derived from the food.I It is impossible, in the present state of science, to say pre-cisely through what series of modifications and intermediateproducts the muscles, the cartilages, &c., pass, in order to beconverted into urine by the action of the oxygen of the

blood-globules. By adding to the formula of proteine (whichis also that of albumen, caseine, fibrine, &c.) as much oxygenas is necessary to transform it into urea, and the excess ofhydrogen and carbon into water and carbonic acid, muchsmaller quantities of the two latter are obtained than thoseproduced in respiration. Here is a numerical example takenfrom the experiments of Boussingault, which I relate for thepurpose of establishing more fully, that the carbon of azotisedaliments converted into urea is much less than that whichanimals emit in the state of carbonic acid. A horse continuedin perfect health when fed upon one and a half kilogrammes(a little more than three lbs. avoirdupois) of hay, and twoand a quarter kilogrammes (about four and a half Ibs. ofavoirdupois) of oats a day. Analytical researches show thatthe nitrogen in hay is 1.5, and in oats 2.2 per cent. Let usadmit that all the nitrogen of the food was reduced in theblood to the state of fibrine and albumen, it would make 140grammes (four ounces, 418 grains avoirdupois) of nitrogenintroduced into the blood, and intended to take the place ofthe nitrogen which escapes with the constituents of the trans-formed tissues. The weight of carbon introduced at the sametime with the nitrogen is 440 grammes, (fifteen ounces, 250grains avoirdupois,) and 246 only of these can be convertedinto carbonic acid during respiration, since the horse partswith ninety-three grammes (three ounces, 127 grains) of carbonin the urea, and 109 grammes (three ounces, 375 grains) in

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the form of hippuric acid. But a horse, according to the ex- Lastly, I think it important to mention here the results of aperiments of this chemist, loses by respiration, in the course great many experiments made by Boussingault, to determineof a day, 2454 grammes* of carbon in the form of carbonic whether nitrogen is expired by granivorous animals, from a.

acid. It is therefore clear, that the carbon of the azotised comparison between their food and their excrements. Byprinciples of the food is only a small part of that which is taking the mean of his results, we find that a turtle dove con-found in the expired carbonic acid. Hence arises the neces- sumes 5.10 gr. of carbon in twenty-four hours; in the same timesity of other kinds of food, as starch, gum, or sugar, and fatty it expels 18.70 gr. of carbonic acid,-that is to say, 9.441 lit. andsubstances, to supply this insufficiency of carbon in the azotised 0.16 gr. of nitrogen,-that is, 0.126 lit. The nitrogen would bealiments. Whenever there is a rapid increase or growth in a hundredth of the volume of the carbonic acid-a proportionthe animal economy, as in young animals, nature has supplied smaller than that found by Dulong and Despretz. The hy-a food in which the proportion of carbon and hydrogen spent drogen consumed in a day is 0.07 gr. These numbers beingin respiration is augmented, by which the azotised materials granted, it results that a turtle-dove, which weighs 187 grammes,destined for the growth of the tissues are economised. and which respires freely at the temperature of z- & to 10

Dr. Capezzuoli has recently discovered, by determining the centig., (46&deg;.2 to 50&deg; Fahr.,) by consuming 5.1 gr. of carbon,weights respectively of the fatty and neutral azotised sub- and0.07gr.of hydrogen in twenty-four hours, can develop thestances in the egg of a fowl, successively as incubation ad- heat necessary to maintain its body at the temperature ofvances, and in the chick itself, after leaving the egg, that z- 41 to 420 centig., (105&deg;.4 to 1070.3 Fahr.,) and that whenabout the seventeenth day of incubation&mdash;that is to say, a exhaling also about three grammes of water by the lungs andshort time before the separation-a diminution in the quantity skin.of both becomes perceptible, and that from this period these It is, then, indisputable that an animal is a real apparatussubstances go on gradually diminishing. It appears that fatty of combustion, in which carbon is constantly burnt, and fromsubstances also are not employed altogether in respiration, which carbonic acid is regularly disengaged. Such a calorific

except when the starch, sugar, and gum, are not sufficient; apparatus has been constituted as to produce a nearly invari-and when this is the case, as in hybernating animals, and able excess of heat in comparison with the temperature of thethose which have remained long without food, their fat is surrounding medium. This excess varies according to theseen to waste. The physiological destination of these sub- rapidity of combustion in this animal calorific apparatus, andstances appears to be primarily for the formation of the according to the constant temperature of the medium in whichcerebral and nervous substance, and to fill the interstices it lives. One gramme of iron which is oxydized in the air,of the cellular tissue, which last is not without importance and a gramme oxydized in oxygen, certainly develop the samein the functions of life, as it there forms a magazine, or store- quantity of heat; but the latter is, perhaps, oxydized in ahouse, for the materials of respiration. second, while the other requires several hours. Hence the

I will now mention the hypotheses of Liebig, with re- immense immediate difference in the heat exhibited by each.gard to the influence of the bile in respiration. Phvsio- Half a pound of grapes heaped together will produce consider-logists ;no longer consider the bile as an excrement merely, able heat in fermenting; the same quantity placed in a layerThis is evident when we reflect that Berzelius found emits the same quantity, yet it is not perceptible, because toobut nine parts only of a substance like it in 1000 parts of much dispersed. It is thus that we are enabled to understandhuman excrement; that is to say, that a man who secretes the difference in this respect between warm and cold bloodedfrom 500 to 700 grammes of it per diem, only loses one animals. We can entertain no doubt of the source of animalfiftieth or one seventy-fifth with the excrements. On the heat. It is found in the chemical reactions of respiration car-other hand, we cannot suppose that a substance contain- ried on in the capillaries,in the transformations of the tissues,ing so little nitrogen should be serviceable in nutrition; and, above all, in the combination of oxygen with carbon.and, lastly, we have just seen that it takes little or no part in I feel it unnecessary to explain the other hypothesis regard-digestion. Liebig is of opinion that, when poured into the ing the source of animal heat. In consequence of the fall of

duodenum, it forms a soluble compound with soda, and that it the thermometer when placed in contact with the tissues ofis absorbed and converted into carbonate of soda by yielding an animal after division of the pneumogastric nerves or thea part of its carbon to the oxygen. These views require to be spinal cord, it was concluded that innervatian was the directsubstantiated by experiment, the more so, that it is only in cause of animal heat; but it was overlooked that by this divi-some pathological cases, and under the influence of certain sion of the nerves and spinal cord, respiration and the circu-atmospheric conditions, that traces of biliary matter have lation of the blood were retarded. Instead of entering uponbeen found in the blood. the discussion of similar hypotheses, it will be more useful toWhether these hypotheses of nutrition be well founded examine more particularly those chemical actions which we

or not, one thing is certain, that an adult man absorbs have considered as the only source of animal heat.about 1015 grammes of oxygen in a day. The observations Philosophers have endeavoured to show the truth of theseof Dumas, Andral, and Gavarret, and those more recently hypotheses: an animal exhales, during a given time, a certainmade by Scharling, give as their result, in the mean, that a quantity of carbonic acid and water, and at the same timeman exhales in one day 224 grammes of carbon, in the state develops a quantity of caloric, which can be measured by theof carbonic acid; that men exhale more than women; and quantity of water it is capable of heating (to a certain degree)children more than men; and that a larger quantity is extri- during the same period. If the carbonic acid and water whichcated during a given time, when awake, than during sleep. the animal exhales are the products of the combustion ofA horse eliminates 2465 grammes of carbon, in the form of carbon and hydrogen, the heat developed by the animal ought,carbonic acid, consuming, for this purpose, 6504 grammes of say philosophers, to be equal to that which the same quantityoxygen. A milch cow exhales 2212 grammes of carbon, as of carbonic acid and hydrogen would produce when burnt incarbonic acid, using 5833 grammes of oxygen. The quantity air.of nourishment must therefore be in proportion to the By recording the results furnished by a calorimeter, intooxygen respired, and the carbonic acid exhaled. The activity which the animal was put, noting the temperature acquiredof the respiratory movements, the density of the air respired, by the water, and measuring at the same time the oxygenand the quantity of carbon introduced with the food, ought to absorbed by the animal, or the products,-carbonic acid andbe proportioned to each other, to preserve the materials of water,-Dulong, and afterwards Despretz, found, that of 100the animal economy. Letellier has lately proved, with birds parts of heat produced by the animal, and ascertained byand guinea pigs, that the quantity of oxygen consumed in re- means of the calorimeter, eighty or ninety only were repre-spiration is less, as the temperature of the air is higher. The sented by the combustion of the carbon and hydrogen fur-carbonic acid exhaled at 00 was found, by Letellier, to be nished by the carbonic acid and water emitted from thedouble that produced at the temperature of from + 15 to 20 animal.centig., (590 to 680 Fahr.) If we remember that the temperature of the animal placedIn animals whose respiratory movements are very active, in the calorimeter is always higher than that of the water

their capillary circulation rapid, and the quantity of blood- which surrounds it, and that consequently the animal is grow-globules very large, the fatty portion of their tissues is very ing cold during the experiment, this cooling may be thoughtsmall. This is the case with birds, the hyena, and the tiger. to afford a plausible explanation of the excess found; and, inIf these animals are allowed but little exercise, fat will accu- fact, the numerous experiments of Despretz have shown thatmulate in their tissues. The experiments of Treviranus teach the excess of heat indicated by the calorimeter, beyond whatus that, when their weight is equal, a cold-blooded animal is owing to respiratory combustion, is greater in proportion asconsumes ten times less oxygen than a mammiferous animal, the animal is young, and its temperature high. Besides, weand nineteen times less than a bird. know, from the beautiful experiments of Edwards, that youngA gramme is 15.44 grains, or nearly fifteen grains and a half. An ounce animals cool much more rapidly than adults.

avoirdupois is equal to 43;.s grains. These considerations are sufficient to show that the excess

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indicated by the calorimeter can be accounted for withouthaving recourse to a special power-a vital property whichengenders heat.

I ought to add, that after the death of the celebratedDulong, an account of various unpublished experiments wasfound among his papers, relative to the heat developed by thecombustion of hydrogen. This heat was much greater thanthat previously found by Dulong himself, and Despretz. Thenumber determined by the latest experiments of Dulong hassince been confirmed by those of Fabre and Silverman. Now,by adopting this new number, we no longer find an excess ofheat indicated by the calorimeter over that developed by thecombustion of hydrogen and carbon, but, on the contrary, adeficiency.There is therefore no motive to seek for other sources of

animal heat than the chemical reaction of respiration andnutrition; but I think it would be wrong to draw an exactparallel between the results of experiments on ordinary com-bustion in a calorimeter, and that which takes place in ananimal, and to admit only one of the numerous chemicalreactions which take place within the same animal as thesource of animal heat. And, in fact, the carbonic acid withwhich venous blood is charged-which is certainly a prodnctof the combination of atmospheric oxygen with the carbon ofthe organic elements of the various tissues which have under-gone some modification-cannot arise from carbon existing ina free state in these tissues, but rather in combinations whichwe are far from perfectly understanding.The experiments of Dulong have now placed it beyond

doubt, that a body, when combined with another, does not pro-duce the same quantity of caloric by burning or uniting withoxygen, which it would emit if it were free. The heat pro-duced by the combustion of bicarbonate of hydrogen, the gasof morasses, or the oil of turpentine, in oxygen, forming waterand carbonic acid, does not equal the caloric which the volumesof gas which compose them would have furnished if burntseparately; it is generally less. The experiments of Hers andAndrews, which were intended to show that in a given combi-nation an absolute quantity of heat is developed, whatever bethe state of the two bodies in union, have, hitherto, only beentried with successive combinations of the same body, as in thecase of sulphuric acid which combines with different atoms ofwater.

If we confine ourselves to the chemical action of carbon andhydrogen with oxygen, to explain the production of animalheat, it will be difficult to account for the results which havelately been arrived at by Andral and Gavarret, in their inves-tigations upon the exhalation of carbonic acid during the actof human respiration. According to the very extensive and,apparently very exact experiments of these two distinguishedphysiologists, the quantity of carbonic acid exhaled duringrespiration may vary much, according to the sex, age, andsome peculiar physiological dispositions. The difference iscomprised between the numbers 5 and 14,4, equally express-ing by these the quantities of carbon (measured in grammes)which are necessary to form the carbonic acid expired in thespace of an hour. The first of these numbers was obtainedfrom a child of eight years old, and the other from a youngman of twenty-six. It is worthy of note, that in children thetemperature is decidedly higher than in adults, but in thelatter, the heated mass being much larger, the loss of heatwhich they undergo must be proportionably great.Andral and Gavarret have also found, that in women the

quantity of carbonic acid exhaled is not increased at the ageof puberty, but that this exhalation becomes more active whenage or other causes put a stop to the phenomenon of men-struation.In spite of this, no sensible difference of temperature is re-

marked in the female body, either before or after, or duringthe time of menstruation, nor in the state of pregnancy. And,without having recourse to the results of experiment, it issufficient to consider, that in some maladies there is a rapiddecrease of temperature; in others, on the contrary, a verygreat elevation throughout the body, without our being able toobserve a corresponding variation in the function of respira-tion.Let us then conclude, that, in the present state of our

physico-chemical knowledge, we may safely admit that thechemical actions which take place in animals during thetransformation of their tissues, under the influence of theatmospheric oxygen, are the source of heat in animals; thatamong these, the combustion of carbon and hydrogen oughtto be considered as the principal but not the only one; andthat further experiments are necessary to discover the exact

relation between the heat produced by an animal or which

arises from chemical reactions which take place within it, andthose which we are able to produce with our apparatus.

I will not leave this subject without mentioning, that invegetables, also, the heat developed by germination is a phe.nomenon of chemical action, occasioned by the combinationof oxygen with the carbon of the germinating grain. It isknown, that in germination there is an absorption of oxygenand a disengagement of carbonic acid; that the diastase con-verts the starch into dextrine and sugar, which afterwardsdisappear as carbonic acid. It is curious, that in plants, asin animals, it is starch and sugar which, by combustion, disen-gage the heat peculiar to these bodies. It is also thus that wemust explain the heat which accompanies the fecundation ofplants, and it is for this reason that we see, in sugar-cane,beetroot, and carrot, the sugar disappear after flowering andfructification.

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PapersON

CHEMICAL PATHOLOGY;Prefaced by the Gulstonian Lectures, read at the Royal

College of Physicians, 1846.BY H. BENCE JONES, M.A., F.R.S.,

PHYSICIAN TO ST. GEORGE’S HOSPITAL.

LECTURE II.MR. PRESIDENT,-It was the endeavour of my last lecture to

trace the forces which are common to vegetables and animals;to discover what they are by what they effect. The simplestforce which we can conceive is a cell-forming force; and findingthat the various structures of vegetables and animals arisefrom modifications in the forms of the cells, we were led toassume the existence of an internal force which causes suchchanges, and thus gives rise to all the varieties of vegetableand animal forms. This modifying force is even more incom-prehensible than that which gives origin to the cells; for theformation of cells, like the formation of crystals, might beconceived as resulting from some property of the elements ofwhich the cells are composed, whilst the modifying force mustbe considered as a force superadded and more analogous tothe higher mental powers in its mode of union with the matterof which living things are composed.In my endeavour to separate the most fundamental of the

forces which make up the sum of life, I have been careful tokeep out of consideration the production of organic substances,and of the liquid, out of which organized forms arise. I wishedto isolate as much as possible the formative forces from allother forces which the cells can exhibit. Such is not, however,a natural separation. Chemistry and the microscope showthat those organs which are similar in form and composition,have the same functions to perform, and similar functions, wefind, are performed by the same matter having a constant form.If this were true in the perfected state of our knowledge,which some centuries hence may be attained, knowing thecomposition and form, we might possibly foretell the function,or, the form and function being known, the composition mightbe predicted, the form having as much influence on the cha-racter of the phenomena as the substance of which that formconsists. Thus, says Mulder, by form and matter, and bymatter and form, all that we observe in Nature is, to a greatextent, determined. This general conclusion is drawn fromthe innumerable phenomena we perceive in the organic world-phenomena which differ whether, on the one hand, the ma-terials are the same, and the forms differ; or, on the other,the materials differ, while the forms are the same. N ot-lvith-standing the high authority of Mulder, I must dissent alto-gether from the opinion, that the composition and functioncan determine the form which the cell assumes. That they,without doubt, have a modifying influence, is easy to admit,and that the mutual relation of these three-composition, form,and function-should, therefore, be the object of our closestinvestigation, is most evident. Still, it appears to me, thatthere is a separate force ever present, and ever acting, whichdetermines the modifications which the cells undergo; keepingthus the sub-kingdoms, classes, orders, genera, species, ofcreated things distinct, and giving rise to that uniformitywhich, in similar individuals, is found to exist.The form and composition of the cell having each an in-

fluence on the function it performs, it becomes a subject of thegreatest importance, to trace the most marked difference in