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that rhythmic phenomena are conditioned duringthe balance of equal and antagonistic oppositeactivities in the antagonistic "half centres "-i.e.,the two efferent neurons to antagonistic muscles. Itis conceivable, therefore, that, even in the absenceof peripheral stimuli, the factors of fatigue and" rebound " in such centres may explain the rhythm.

But Dr. Brown’s experiments have shown that withthe degree of narcosis he employed both these factorswere eliminated. He suggests that the activationof the half centres may be fundamentally con-ditioned by a stimulus equivalent to the bloodstimulus in respiration. Such stimuli may beslight in degree; but it is known that stimulus ismost effective when there is a close approxima-tion to an equal and opposite activation of thehalf centres, so that slight changes would besufficient. So far, the reasoning is certainly infavour of the truth of the writer’s contention.There is next to be asked, however, Of what valueare the peripheral stimuli’? Do they count fornothing ? It is suggested, and here certain facts,of evolution enter into the argument, that the

spinal reflexes which excite progression are in thenature of distortions of the "beat" of the funda-mental rhythm. The fundamental rhythm, being,as the experiments showed, the last to be abolished,is essentially of more primitive and fundamentalorigin. Originally it was possibly conditioned bycircumstances closely allied to the more elementalblood stimuli with its asphyxial changes and inthe mechanisms of which afferent organisedchannels played no part. It was the later organi-sation which added higher complexity. The reflexwas grafted on, as it were, to the fundamental

rhythm. Such an addition is represented by thenormal reflexes of progression, and this now

dominates, by distortion of the original beat, theoriginal rhythm. But it remains a superimposi-tion. It is not, in essence, the fundamental nervousmechanism. We see in this paper a carefullyreasoned case against the currently accepted view,and one which must meet with a measure of

acceptance until further evidence is forthcoming.

THE RELATION BETWEEN DEFECTIVE ANDPROLIFIC STOCKS.

THE paper by Mr. M. Greenwood, jun., and Mr. G.Udny Yule on the Determination of Size of Familyand of the Distribution of Characters in Order ofBirth from Samples taken through Members of theSibships is one of considerable importance in thatit impugns on statistical grounds statements madeon high statistical authority, which if true would-10ive serious cause for alarm. These statementsare, first, that defective stocks are more prolificthan the normal; and, secondly, that the earlier-born members of a family are more liable toexhibit defects than the later born. The signifi-cance of the latter view rests on the fact that thedecline in the average size of the family, which has Iindubitably taken place in recent years, meansthat the proportion of first- and second-bornhas increased. Both circumstances would thuslead to an increasing prevalence of defect.Mr. Greenwood and Mr. Yule express their criti-cisms in a mathematical form, but the principleson which their reasoning is based are quiteeasily intelligible to persons without mathematicaltraining and appear obvious when pointed out.Bulletins No. 10A and 10B of the Eugenics Record

1 Journal of the Royal Statistical Society, vol. lxxvii., Part 2,January, 1914.

Office (Cold Spring Harbour, Long Island, NewYork) contain the report of the " Committee to

Study and to Report on the Best Practical Means ofCutting Off the Defective Germ Plasm in theAmerican Population." No. 10 A describes thescope of the committee’s work and No. 10B the"

Legal, Legislative, and Adminstrative Aspects ofSterilisation." The latter contains a valuable

summary of the sterilisation laws which have beenpassed in 12 States of the American Union, and ofthe Bills introduced in other State legislatureswhich did not become law, but were either thrownout or vetoed by the governor or revoked byreferendum. The result of all this legislativeactivity has been very meagre. In only threeStates have any sterilisation operations been per-formed under the statutes-namely, about 300 inIndiana, 268 in California, and 7 in Connecticut.At the present time no operations of this kind arebeing performed as the constitutional nature of thelaws is in question. But although they are dormantit would be premature to conclude that they aredead.

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"LOCALISED" TUBERCULOSIS IN THE PIG.

A REPORT made to the Local Government Boardby Dr. A. Eastwood and Dr. F. Griffith,1 which hasbeen issued recently, gives the results of a valuableseiies of observations on the distribution of visibletuberculous lesions and of tubercle bacilli in a con-siderable series of pigs selected at the slaughter-house as examples of minor degrees of pigtuberculosis. The term "localised" tuberculosisis often loosely used in meat inspection, but inthe sense in which it is used in this report it

signifies disease which as a result of naked-eyeexamination is apparently confined to the lymphaticglands in relation to the alimentary tract. It isclear that among the ordinary pigs which cometo the slaughter-house tuberculosis which is

actually localised in this way is much lesscommon than tuberculosis which is more or

less widely disseminated. Thus at the Brightonabattoir, from which a large part of thematerial was obtained, 24,144 pigs were exa-

mined during the period of selection, of which209 were reported by the meat inspector to beaffected by general tuberculosis, 393 had slightlydisseminated tuberculosis, while localised tubercu-losis was present in only 59. The pig, as the workof the Roval Commission on human and animaltuberculosis showed, is susceptible to infectionwith various bacilli of mammalian type (includingbovine and human) and with avian bacilli. By farthe most common source of its natural infection isthe bovine, derived from tuberculous milk or fromthe tuberculous fiscal discharges of cattle; but avianinfection may also arise from ingestion of theexcreta of fowls affected by the disease, while inone or two of the series here reported on thebacilli were found to be of the eugonic type,of low virulence for rabbits, indicating a humansource of infection. Avian infection in the pigappears to have much smaller tendency to dis-semination-when judged by the presence of naked-eye tuberculous lesions-than bovine infection. Asa rule, though not invariably, when infection wasdue to avian bacilli the affected glands were eithernot enlarged or only slightly so; and they con-

tained gritty or calcareous nodules which wereeasily shelled out of the surrounding tissue, leaving

1 Reports to the Local Government Board on Public Health andMedical Subjects. New Series. No. 91. Price 3s.