A H.EMOGKEGAKINE OF MAMMALS 101 



The nucleus, it may be said, stretches completely across the body, entirely separating 

 the anterior from the posterior moiety. The broadest part of the parasite is towards the 

 posterior end of the nucleus. 



2. In most cases a third stage can be readily demonstrated. This is chiefly seen in 

 tile liver and kidney, organs where the circulation is slow, and will probably be found also 

 in the bone-marrow and brain. Indeed, some smears of the bone-marrow have shown what 

 were probably empty cytocysts. In thick smears from the liver and kidney well-defined 

 cysts are found, the walls of which are apparently formed by the remains of cells of these 

 organs which have been destroyed by the parasitic growth. 



These cysts vary much in size. The largest I have noted occurred in a liver smear and Cytocysts and 



" " . 11.1 merozoites 



measured 396 /x by 336 ^. A common dimension appears to be about 224 p, by IBS i^, but 

 many smaller cysts occur. 



It is usual to find some of these cytocysts empty, or at*the most containing a little ^'^§^ °^ 

 residual protoplasm, but a certain proportion are found to contain merozoites, readily 

 recognisable by their shape and nuclei, and somewhat resembling the trophozoite stage in 

 the blood. Their nuclei, however, are compai'atively small, and in many cases the merozoite 

 appears to be longer and more pointed at the ends than the endoglobular trophozoite. Early 

 schizont forms also occur, in which the protoplasm contained within the cyst wall has not 

 become differentiated and stains more or less uniformly. Sometimes darker-staining portions 

 indicate the future nuclei of the merozoites. When complete division has taken place some 

 residual protoplasm remains behind, and the whole condition is very like that which has 

 been described by Labbe* in the case of Kari/ol/jsux laccrtarum . Sections of the liver stained 

 by the Giemsa method show all stages of the schizonts. Mitosis of the nuclei and the 

 formation of daughter nuclei are well seen. 



Appearances very like those presented during the schizogony of some of the Coccidia, Resemblance 

 notably Adelca ovuta, are exhibited and the whole condition from the invasion of the liver to the Coccidia 

 cell to the bursting of the cyst and the freeing of its contents can be traced. 



By what channel the hepatic cell is invaded has not as yet been determined, but it is 

 probably through the capillaries. (Vide infra.) 



The interesting appearances presented by these liver sections (Plate XII.), which were 

 kindly prepared for me by Mr. Richard Muir, of the Pathological Department, University of 

 Edinburgh, from embedded tissue which I took home \\ith me, have been further studied in 

 sections prepared and stained in the laboratories. These sections were stained, by 

 haematoxyliu and eosin, by the Giemsa and Leishman methods, and by Heidenhain's iron- "'^' ^^"^"""^ 

 hsematoxylin process. Ordinary free forms of the hfemogregarine such as are met with in 

 the peripheral blood could be seen, and on one occasion I found such a form lying in close 

 apposition to the nucleus of the endothelial cell of a capillary, which observation probably 

 indicates the channel of invasion. As regards development the earliest appearance seen is 

 that of a large, pale-pink (Giemsa or Leishman stain), body of an oblong or nearly spherical 

 shape occupying a cavity which has been formed in a liver cell. The body varies in size. 

 One which was measured gave the following dimensions : Greatest length, 12 fi ; greatest 

 breadth, i.e., at nucleus 7'5 n. Another measured 12 /n x 6 /i. The nuclei of these bodies 

 are small and spherical, centrally-placed, and stain chromatin red. They are found to be 

 undergoing mitosis. I believe these bodies to be trophozoites which have become enlarged 



• Arch. Zool. Exp. ct Gen. (3) ii. 1894. 



