264 H. M. WOODCOCK. 



a Trypanosorae, and the connection between these newPiro- 

 plasraa-like forms and a Trypanosome — or, at any rate, a 

 HaBinoflagellate — has been definitely established by the work 

 of Rogers, to which allusion has several times been made. 



The parasites with which Rogers experimented were splenic 

 forms taken from cases of cachexial fever and Kala-azar. 

 As the author himself admits, the artificial conditions in which 

 the organisms were cultivated cannot be supposed to have 

 been as favourable to their further development as the natural 

 conditions, whatever these may be, which bring about the 

 same changes. Hence there must be, for the present, more 

 or less uncertainty as to how far the forms described accur- 

 ately represent typical evolutive stages of the parasites. Some 

 of Rogers' figures certainly suggest the idea that the parasites 

 were unhappy at the time he portrayed them.^ 



However, the great fact remains, that what were unmis- 

 takably Flagellate forms developed in the cultures at different 

 intervals. Fig. 87 IV shows two pear-shaped forms, lying 

 side-by-side after binary division, one of which has developed 

 a flagellum near one end. This was in a culture of the third 

 day. Another pair of pyriform stages with longer flagella, 

 belonging to a fourth day culture, is seen at IV e. The 

 most convincing stages (IV cj) developed suddenly in a 

 one-day culture from another patient. Rogers accounts for 

 this by the condition of the blood being less altered than 

 after three or four days' incubation. Probably, also, the 

 organisms, when they left the host, were in a more favourable 

 condition or phase for further development than in the other 

 cases. In nearly all instances, the flagellum originated from 

 that side or end of the body, near which the smaller nucleus 



' Among these are one or two rather indefinite forms which Rogers con- 

 siders represent stages in fusion (comparable to conjugation) ; earlier stages 

 in the process are, the author thinks, exemplified by many of the pairs or 

 couples (e.g. those in fig. 37 IV d). The writer does not consider this 

 very likely ; the couples much more probably represent individuals which 

 have not yet separated after division (cf. the figs, of Donovan, and Laveran 

 and Mesnil), the somewhat atypical form and arrangement being readily 

 accounted for by the medium in which the parasites are. 



