262 H. M. WOODCOCK. 



Rogers the largei' and smaller cliromatic elements (in other 

 words, the trophic and kinetic parts) remain distinct and 

 divide up independently (fig. 37 IV 5). Laveran and Mesnil 

 consider that the very young forms observed, with only one 

 nuclear body, result from the segmentation up of such a 

 stage with several similar nuclei. Rogers (1. c.) has followed 

 the process in parasites kept in citrated blood, maintained 

 at a temperature considerably below blood heat. Fig. 37 IV c 

 represents, according to this author, practically the end 

 stage in the multiple division of a parasite, a group of young 

 daughter forms, each with two chromatic masses, being seen 

 embedded in a faintly-staining ground substance, which, 

 there can be little doubt, is of the same nature as the 

 zoogloeal matrix above discussed.^ Further investigation is 

 necessary to ascertain the particular circumstances which 

 bring about the occurrence of these two varieties — if they 

 ai'e really distinct. 



The above is a summary of all that was known concerning the morpho- 

 lo<^7 and development of this parasite prior to the quite recent announce- 

 ments of Rogers, and many and various have been the views expressed with 

 regard to its nature. Leishman, the discoverer of the splenic form, at 



' Rogers considers that this ground substance is derived from the organ- 

 ism itself, and consists of residual cytoplasm not used up in forming the 

 daughter individuals. In other words, the author, to judge from his 

 description and figures, regards the daughter parasites as being formed 

 within the body of the parent; i.e. this is an instance of endogenous 

 multiplication. The writer does not agree with this conclusion, as all our 

 knowledge, both of Trypanosomes and Hajmosporidia — as well as of other 

 Sporozoa derived from a Flagellate ancestor — goes to show that multiple 

 division is uniformly exogenous or peripheral, and quite distinct in 

 character from the endogenous type (cf. the preceding pages and see 

 Minchin, 1. c). Rogers figures another similar group of young forms — 

 still clustered together — in fresh blood from tlie spleen ; in these there is 

 no sign of residual matrix. It is much more probable that Christophers' 

 explanation holds good here also. Rogers mentions that the parasites (in 

 the cultures) are in a slimy or zoogloea-like matrix, which develops in the 

 course of a day or two, and this is doubtless due to the alteration and 

 breakdown of splenic cells, blood corpuscles, etc., in which the parasites are 

 developing. 



