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seem to yield first in its horizontal ramus, when Ithere must be a fracture also somewhere betweenthe symphysis pubis and the tuber ischii." In the

present case the injury stopped short of crushingand displacing the bones. The absence of sub-

jective symptoms was due to the subperiostealnature of the fracture, there being even not enoughdisplacement to involve the bladder. Perhaps it

escaped because it is chiefly an abdominal organ inchildhood. But for the ecchymoses and the

wincing on examination arousing suspicion sufficientto resort to skiagraphy the fracture would haveescaped detection. ____

METAPLASTIC BONE AND MARROW FORMATION

IN VESSEL WALLS.

IN the Cleveland Medical Journal for November,1913, Dr. H. 0. Ruh has published an importantpaper on a subject which has not received frompathologists the attention it deserves-metaplasticbone formation in vessel walls. Radiography hasrecently brought to light many examples of calcifica-tion and ossification in unusual situations, especiallyin arteries and veins. Dr. Ruh reports the followingcase. A woman, aged 58 years, was admitted intohospital suffering from dyspnoea and swelling of thelower limbs. At the age of 30 years she had anattack of rheumatism, from which she recoveredwithout cardiac symptoms, but during the last eightyears she had suffered from cardiac distress. Onexamination mitral regurgitation and obstructionwere found with failure of compensation. The urinecontained albumin and a few epithelial cells. Shedied soon after admission. At the necropsy about1000 c.c. of serous fluid were found in the peritonealcavity, and the liver reached 4 cm. below the costalmargin. The heart was greatly enlarged and

weighed 675 grammes. The right auricle andventricle were much dilated and formed the

greater part of the organ. The mitral valvewas reduced to a slit-like aperture by fusionof the cusps and fibrous thickening. Theaorta throughout was thickened and scarred andshowed numerous atheromatous plaques, athero-matous ulcers, and calcified areas. Below thecoeliac axis the atheromatous process was espe-cially marked. Just above the bifurcation a shelfof dense hard tissue with irregular edges projectedinto the lumen. On its upper side was a greyish-red thrombus which further occluded the alreadynarrowed lumen. About 1 cm. above the bifurca-tion of the aorta was a pinkish-grey occludingthrombus firmly attached to the wall. Thisextended downwards into the common iliacarteries for a distance of 3 cm. in the left and2 cm. in the right. On the right side the thrombuswas evidently more recent than on the left; it wasmore pinkish and not so dense. On the left sidethe thrombus was completely organised, very dense,nearly white, and cut with much resistance. Infact, the vessel suggested a fibrous cord. Theiliac arteries just below the thrombus were

much sclerosed. There was also moderategeneral arterio-sclerosis. Microscopic examinationof the aorta below the shelf mentioned showedgreat thickening of the adventitia and degenera-tion of the elastic fibres of the media. Aroundone-half of the vessel, partly in the mediaand partly in the intima, was an area com-

posed’ of osseous tissue with large spacescontaining red marrow in which all types ofmarrow cells were present. In the neighbourhood

were large collections of osseous deposit. Thebone showed a definite lamellar structure andnumerous typical bone corpuscles. With highmagnification a layer of cells resembling osteo-clasts, and forming a membrane covering theosseous tissue, could be found. A number of scat-tered cases of heteroplastic bone formation can befound in medical literature. The following siteshave been given: vessel walls, mucosa of the

bladder, laparotomy scars, lung, pia and choroidplexus, dura, pleura, eye, stomach, liver, lymphnodes, heart valves, adrenals, and testes. Morecareful examination would probably show thatthe condition is commoner than is supposed.Kryloff estimates that in 15 or 16 per cent. of allcases of advanced arterio-sclerosis there is boneformation. In 1826 Andral described a case inwhich it was present in the aorta of a girl aged8 years, and five or six cases in patients betweenthe ages of 16 and 24 years. He also referredto a case of ossified temporal artery in an

infant aged 15 months. Howse in 1877 foundin an axillary artery a focus of bone. In 1866Paul demonstrated at the Pathological Society ofLondon a portion of a sclerotic tibial artery with afocus of osseous tissue in the intima. Consider-able experimental work has been done on meta-plastic bone formation. It has been produced inthe kidney by ligature of the renal artery. Caremust be taken in calling a process metaplasia, asthe distinctions from various processes of growthare not so sharply defined as is generally supposed.Ziegler defines metaplasia as "that process bywhich a fully developed tissue is changed intoanother tissue without passing through an inter-mediate cellular stage." It is a well-knownphysiological process and occurs at all periods oflife. The most common examples are the con-

,

version of connective tissue cells into fat cells andof cartilage into bone. Such closely allied pro-cesses as heterotopia, in which there is a congenitalor acquired snaring of cells of a tissue with sub-

sequent growth out of place, must not be con-

founded with metaplasia.

SLEEPING SICKNESS IN THE ISLAND OFPRINCIPE.

WE drew attention recently 1 to the hopefulattitude adopted by Professor John L. Todd, ofMontreal, regarding the possibility of ultimatelypreventing the occurrence of human trypano-somiasis in tropical Africa, notwithstanding thesomewhat gloomy opinions expressed by some otherexperts upon the subject. Since then we haveseen a report on sleeping sickness in the island ofPrincipe, written by Surgeon-Captain Bernardo F.Bruto Da Costa, chief of a commission appointed bythe Portuguese Government in 1912 to investigatethe prevalence of the disease in the colony. This

report gives a sanguine view of the situation, andgoes so far as to say that if the means indicatedby the commission were provided by Govern-ment the malady could be eradicated withina year. It has, however, to be borne in mindthat the problem is less difficult in Principe,an island some distance from the Africanmainland and with a population numbering not

1 THE LANCET, Dec. 13th, 1913, p. 1709.2 Sleeping Sickness in Principe. By Surgeon-Captain Bernardo F.

Bruto Da Costa, Chief of the Sleeping Sickness Commission. Trans-lated by Lieutenant-Colonel J. A. Wyllie, I.M.S. (retired), Associate,Centro-Colonial, Lisbon. London: Baillière, Tindall, and Cox. 1913.Pp. 90. Illustrated. Price 2s. 6d. net ; postage 3d. extra.