SCHIZOGONY OF TRYPANOSOMA EVANSI. 59 



the nucleus. They bear a resemblance to the Leishman-Dono- 

 van bodies. I have not been able to distinguish a blepharo- 

 plast-less variety corresponding to the female type of schizont 

 described by Chagas in Schizotrypanum cmzi. Sometimes the 

 blepharoplast lies closely applied to or over the nucleus, where 

 it is distinguished with difficulty. These bodies do not appear to 

 be surrounded by a definite wall or limiting membrane, but are 

 probably bounded by the periplast of the trypanosome. 



In the spleen of guinea pigs killed when the blood is swarming 

 with trypanosomes, a further development of these bodies is 

 evident. The round binucleated body increases in size, and 

 concomitantly a multiplication of both nucleus and blepharoplast 

 takes place. The first evidence of these nuclear changes is 

 seen in forms like that shown in fig. 5 which contains one 

 nucleus but in which the blepharoplast has divided. Succeed- 

 ing stages containing 2, 4, 6, and 8 nuclei, and blepharoplasts are 

 shown in figs. 6 to 10. The fully developed schizonts are round 

 in optical section and measure 10 to 15 microns in diameter. 

 The average number of nuclei and blepharoplasts appear to be 

 8, but the number varies from 4 to 16. Some of the large 

 schizonts (fig. 11) show evidence of fission of the protoplasm, 

 and others (fig. 12) show a complete division and differentiation 

 of the merozoites, surrounded by a thin cyst wall. In schizo- 

 cysts that are not ruptured or deformed the merozoites appear to 

 be arranged like the segments of an orange, but with a slight 

 spiral twist. The merozoites are elongated, sickle-shaped bodies, 

 6 to 10 microns long and 1 to 1.5 microns broad, are without 

 undulating membrane and flagellum, and have a nucleus situated 

 near the center and a blepharoplast near one end. 



The merozoites of Schizotrypanum cruzi, according to Chagas, 

 escape from the cyst and penetrate red blood-corpuscles of the 

 host where they develop into adult trypanosomes. Buchanan, 

 also, observed ring-form, binucleate parasites and all stages of 

 the development of these to adult trypanosomes in the red blood- 

 corpuscles from the spleen of the gerbil infected with Try- 

 panosoma briicei. Forms, corresponding to these intra-corpus- 

 cular stages of Chagas and Buchanan, are frequently seen in 

 the smears from the spleen of guinea pigs infected with Try- 

 panosoma evansi, but in no case have I been able to convince 

 myself that the parasite lay within the red corpuscle. In spread- 

 ing a smear of the spleen pulp containing many trypanosomes 

 it must frequently happen that a parasite will lie over, under, 

 or around a red corpuscle; and in drying such a smear the 



