102 A H.KMOOnEOARINE OF MAMMALS 



iuxl .swiillcii |>ri(ir to ilivisimi. As a n-siilt of its iiicri'iisc in sizi- within tin- liciiutit- cell, a 

 snntll cyst is fornifd n\ tin- i-xpcnst- of tlu- sulistanci- of tlif cell, tlic nncleiis of which ^cts 

 |pushiil ti) line siilc. Till' wall of this cyst, foiincil from the compressed cell |iroto|iliism. 

 licconics Very well dcfincii, and as a rnle a space is left hctweeii the liody and the cyst wall. 

 What I lielievi' to lie the next stage is evidenced by the presence of one or more cnrveil 

 bodies in these snnill cysts, together with what I take to he the remains of the original hoily 

 from which these ciirvcil forms iiavc been derived bv a jiroccss of micliar division. 

 (Plate X 11.) 



'rilese cUrMil fiiriil.-i rather rcseliiliji' the trophozoites of tile blood, but tiiey diti'er from 

 these latter in having small sjiherical nn( lei, often seen nndergoing mitosis, and in the fact 

 that as a rnle they are more curved and somewhat lai-ger. 'I'liey were found to measure from 

 !• fi to Id") f, in length by 'A ft in breadth. They arc often somewhat club-shaped and their 

 cytoplasm stains a bluish-purple and their nuclei take on a chromatin reil colour. What 

 I think represents the residual cytoplasm of the mother body is usually seen as a pale pink, 

 non-nucleated spherical nuiss lying in the concavity of one of tiie.se curved forms. (Plate XII.) 

 It rather suggests a so-called polar body and is not seen when more than three of the curved 

 forms e.vist in the cyst. When several of tlie curved forms are present one finds that they 

 are lying at dilt'erent levels. Thus only two nniy be visible at first, but on focussing either 

 up or down a third comes into view lying, it mav be, across the otiier two. J)ivisiou has 

 evidently taken place in different planes. 



The stage which follows is that of the undiflcreutiated .scliizont. (I'lalc Xil. A more or 

 less spherical mass of protoplasm, staining a dark blue colour, is found lying in the cyst, which 

 has become larger. Cysts at this stage, often measure 12 /i in diameter. The contained 

 scliizont nia.ss varies in size and is often about 8 ft across. Differentiation takes place, 

 evidenced by the appearance of nuclei which arc seen studded, so to speak, all over the 

 schizont mass or arranged round its periphery. (Plate XII.) When the latter is the case a 

 very pretty appearance is exhibited. Tiie cyst is found to have undergone further enlargement, 

 connnon measurements at this stage being 2"i'5 /» to '2h-^ n in greatest diameter. Sometimes 

 no space exists between the substance of the hepatic cell and the dividing mass. In such cases 

 the cyst wall is ill-defined. As a rule, however, liotli unstaiiu'(l space and wall arc widl marked, 

 while the nucleus of the hepatic cell has citlier wIkiHv vanished or has liecoiin' nnuli llatteueil 

 out and in conseiiuenee has taken on an oblong or spindle shape. Very little of the liver cell 

 is left, and in the next stage, that of division resulting in the formation of the mcrwzoites, it 

 is common to find it represented merely by the cyst wall which is often thicker in some parts 

 than in others. 



The final division is seen at several different stages, and it appears to be complete, no 

 residual protoplasm being left. The nierozoites all present the same ai)pearauce and are 

 much the same size. (Plate XII.) Those which 1 have measured were abiuit (i ft in length 

 by p.')/! in bnadtli. They stain a [lale red m- |iiid< aii.l tlnir nu<lei tal<r nii an intense 

 ehronnitin red colour with Giemsa or Leishnnin stain. Tluy are very slightly, if at all, 

 curved and are found crowded together, lying at different levels and in divers directions, 

 or arranged synniietrically round the periphery of a portion of the schizont nuiss which 

 has not yet proceeded in division. 



The final stage is evidenceil by the bursting of the cyst and the freeing of the nierozoites 

 which doubtless pa.ss into the blood stream and invade the red blood corpu.scles, thus starting 

 once more the cycle of schizogony. (Plate XII.) Emjity and shrunken cysts can be seen 



