162 Mr. G. Buchanan. Note on Developmental [May 12, 



day, beginning on the first day after injection. Films from the peripheral 

 and heart's blood were taken, and smears from the lung, liver, spleen, bone- 

 marrow and axillary glands were made, these being fixed and stained by 

 various methods. 



As both the intra-corpuscular forms and those which possibly represent 

 encysted stages appeared in the spleen on the fifth day in the first gerbil, a 

 careful examination of the films in the first series up to that time was made, 

 but none of the forms seen in the original slide were recognised. In the 

 other series, however, examination of spleen smears from gerbils chloroformed 

 on the sixth and seventh day respectively revealed both of the forms 

 mentioned. These were also usually obtained in subsequent independent 

 cases on the seventh and eighth day. 



Morphology and Development in the Spleen. 



(a) Intra-corpuscular. — No definite merozoite forms as described by Chagas 

 were ever seen entering the red cells, and the small inclusion shown in 

 Plate 3, fig. 3, was the only appearance observed which suggested a 

 merozoite. Speaking generally, the smallest intra-corpuscular forms met 

 with took the shape of very small rings with two chromatin masses, and were 

 about one-third the size of the red blood cell. Nearly all stages from this 

 to a fairly mature trypanosome, contained within the limiting envelope of the 

 red cell, could be traced, the intermediate stages in many cases being similar 

 to those of Schizotrypanum cruzi. This fairly mature trypanosome, however, 

 possessed neither undulating membrane nor flagellum. Some of the more 

 mature forms were coiled up or S-shaped, every part of them being wholly 

 within the corpuscle. These varieties were not so numerous as the complete 

 ring forms. The blepharoplast was not recognisable in all cases, but, when 

 present, was usually situated at the thinnest part of the ring. 



(b) Extra-corpuscular. — Eing forms were also met with free in the plasma, 

 and these impressed one as being possibly encysted and likewise showed a 

 development similar to that seen in the red cell. Numerous small solid, 

 encysted (?) forms appeared in the spleen on the fourth day in one gerbil, 

 and these, as a rule, were also present in other animals in the bone-marrow 

 and axillary glands on and after the sixth day. The very small types 

 appeared as spherical masses of densely-stained blue protoplasm, the nucleus 

 in some being indicated by a small undefined violet mass, while the blepharo- 

 plast was detached. 



Bound the spherical body here described there existed, as a rule, at least 

 when development was somewhat advanced, a clear area which gave the 

 impression that the protoplasmic mass was lying in some form of vacuoloid 



