69(3 H. M. WUOJJCUCK, 



infrequent. A few are iiiediuin in size (fig. 135), but most 

 of them are small (figs, 137, I'SH, and 139). It is quite 

 obvious from their appearance tliat these forms of the 

 parasite, in the culture at any rate, are not merely " resting," 

 persistent j)hases, but ai-e degenerating and dying. And it 

 is interesting to note that the process of degeneration takes 

 place by a gradual disappearance of the nuclear elements. 

 These no longer stand out, sharply stained, in the cell. They 

 lose their distinctive affinity for the stain and become less 

 and less distinguishable from the general substance of the 

 body ; at the same time they tend to diminish in size, as if 

 they were being dissipated in the cytoplasm. The last stage 

 of the parasite is an indefinite body, which stains a dull or 

 faint red. Hence, so far as the cultural forms are concerned, 

 all the evidence I have goes to show that the loss of the 

 flagellum means a])proaching degeneration and death (con- 

 trast, for example, the parasite of fig. 136 and that of 

 fig. 138, which are on the same slide and within a few fields 

 of each other). 



The above description includes all the different types and 

 the chief varieties of form which I have observed among the 

 trypanosomes in cultures. 



Agglomeration. — I have, next, a few observations to 

 make upon the charactei-istic feature known as agglomeration. 

 I have seen many instances of this occurrence in my cultures. 

 I have never found it in early original cultui-es (i.e., of less 

 tliMU six or seven days), nor in subcultures. Agglomerated 

 clusters are only met with when the paiasites have become 

 abundant in the medium. The clumps are of all sizes, from 

 small ones composed of a few individuals (a dozen or less) 

 up to large masses containing hundreds of parasites. Xow 

 and again, in these large aggregations, the parasites are 

 clustered round more than one centre, i.e. in these cases 

 there is an approach to the condition of secondary agglomera- 

 tion, distinguished by Laveran and Mesnil from primary^ 

 (single) clusters. In all the clusters seen the parasites have 

 their flagella directed towards the centre of the rosette. 



