226 H. M. WOODCOCK. 



it were, as the nucleus of a large secondary agglomeration ; here, if dispereion 

 does not soon take place, the individuals comprising it rapidly degenerate 

 and die, owing to their confined and unfavourable situation. 



The significance of the process has yet to be ascertained. By some it is 

 considered as a purely involuntary proceeding on the part of the parasites, 

 and brought about mechanically, by the operation of external influences.^ 

 The clusters of paralysed and dead Trypanosomes which may be formed are 

 adduced in support of this view. Prowazek's explanation (1. c.) is that 

 nuclear substances resulting from the partial break-up of the kinetonucleus 

 are passed out, causing the surface of the body near that end to become 

 sticky and viscous ; and this brings about agglomeration. McNeal (1. c.) 

 also considers that the agglomerating end of the parasites is sticky and 

 adhesive. Neither he nor other workers, however, have described such a 

 fragmentation of the kinetonucleus in Trypanosomes constituting typical 

 rosettes (cf. fig. 20b), this organella usually appearing quite normal.'' In 

 view, also, of the fact that the parasites may disagglomerate, it does not 

 seem probable that the disorganisation of the kinetonucleus is the cause of 

 agglomeration. 



On the other hand some authors (e. g. Bradford and Plimraer [6], and 

 Stassano [108, 109]) have seen in the binary unions of T. brucii an occur- 

 rence more or less comparable with the conjugation of Infusoria. There can 

 be no doubt that this is too extreme a view to take, there being certainly not 

 sufficient ground for supposing that conjugation in the strict sense, i. e. 

 with nuclear fusion, etc., is here taking place. What evidence there is, is 

 entirely against such a conclusion. In the first place agglomeration can 

 scarcely be considered, as an integral part of the life-cycle. The process is 

 the more entire and lasting, the more unfavourable the conditions which 

 induce it. Indeed, complete fusion is not known to occur (even in binary 

 unions) except in those cases where the parasites are powerless to liberate 

 themselves, when they gradually coalesce and degenerate (see below). 

 Again, it is almost certain that a true conjugation, in the form of the union 

 of differentiated gametes, occurs at quite a different stage of the life-cycle. 



^ Laveran and Mesnil say that there is sometimes to be noticed, at the 

 centre of a rosette, a leucocyte or hiematoblast which may, perhaps, have 

 served as a nucleus of attraction (cytotactic or chemiotactic) for the indi- 

 viduals of that cluster. 



- It seems to the writer uncertain how far these parasites with the 

 kinetonucleus broken up into fragments (as was frequently the ease, 

 Prowazek says, in agglomerated clusters) ought to be regarded as normal 

 forms; for in addition, in one or two of Prowazek's figures, vacuolisation 

 is much in evidence. Hence it is not unlikely the parasites were somewhat 

 altered and commencing to degenerate (see also below, under "Chromato- 

 lysis"). 



