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Haemoflagellates , etc. 
a developmental process, while the latter is brought about by certain 
unknown changes in the medium in which the parasites live. Herpeto- 
monas and Crithidia, as far as we have studied them in the intestinal 
juices of insects, agglomerate in their adult stages by their flagellar ends; 
and it is a physiological process. Adult Trypanosomes however collect 
together by their aflagellar ends and this change takes place under 
unfavourable conditions ; it is doubtful whether it naturally occurs 
in the blood of vertebrates. It is therefore most probably a pathological 
process. In the case of T. lewisi it is well seen when the serum of a 
rat, inoculated two or three times with this trypanosome, is added to 
blood rich in parasites. Laveran and Mesnil consider this process is 
brought about by a specific agglomerin. The agglomeration of Herpeto- 
monas and Ci'itliidia in the intestinal fluids of insects is therefore by no 
means comparable with the agglomeration of vertebrate trypanosomes 
under unfavourable conditions. Can we then attach any great im¬ 
portance as Woodcock does to the different methods of agglomeration ? 
The process of conjugation is hardly worth mentioning as there is not 
a single instance in which it has been described from Haemoflagellates; 
the so-called examples of conjugation, T. lewisi and T. brucei (Prowazek), 
represent something quite distinct, for example in the case of T. lewisi 
from the louse they are undoubtedly Crithidia dividing unequally. 
The majority of trypanosomes we have studied travel forwards by 
their flagellar ends, except perhaps the very stout forms of T. rotatorium. 
It should however be remembered that we are only able to observe the 
movements of these flagellates under artificial conditions; the very best 
instruments we can employ can hardly replace the conditions in the blood 
of the host. Are we to understand then that the slow crawling move¬ 
ments of certain trypanosomes on slides, when they move by their 
aflagellar ends, are their normal methods of locomotion ? We are not 
sure of this and we would hesitate to attach any great importance to it. 
Considering then more closely all the biological data brought forward 
by Woodcock to support the view, that the non-flagellate end of a 
trypanosome is the sensitive end, we find that the majority of his 
arguments are open to grave criticism, and the only point we might 
concede him is the possible progression of some trypanosomes by their 
aflagellar ends under unfavourable conditions. 
Under the heading “morphology ” Woodcock lays stress on the cell- 
vacuole situate in the aflagellar end of certain trypanosomes, T. leivisi 
and T. gambiense. Are we to consider this a normal cell constituent, 
and does it represent the (original) contractile vacuole of an ancestral 
