W. S. Patton and C. Strickland 
325 
appears to have overlooked the possibility of the fly having parasites in 
its stomach before it fed on the fowl. Further, we find that this 
particular fly was bred from a pupa in August 1905, and that it was 
kept in a fly cage in which presumably other wild flies had been kept, 
so that it is not impossible for the fly to have ingested cysts of T. grayi 
passed out in the cage in the faeces of other flies, and as it was not killed 
till October 10th, 1905, there was ample time for this to take place and 
for the parasites to germinate; we think this is in the highest degree 
probable. It is fruitless to discuss this point any further; far more 
exact experiments and proofs are required before it can be accepted 
that T. grayi is an avian trypanosome. 
Koch (1905) was the first to study the development of pathogenic 
trypanosomes in the Glossinae, G. palpalis. He states (1907) that he 
observed the development of T. gambiense in Glossina fusca and 
Glossina tachinoides. He differentiates the parasites into short and 
slender forms, zygotes with many nuclei which give rise to small forms. 
All Koch’s attempts to inoculate animals with these forms have however 
proved negative. It is really difficult to see what connection these 
so-called developmental forms have with T. gambiense. Koch now 
regards the crocodile as a source of blood supply for tse-tse flies, and, 
in consequence of his statements it has been gratuitously assumed, 
more especially by the lay press, that the flies obtain the pathogenic 
trypanosomes from crocodiles. This assumption is entirely unjustified. 
Turning now to Stuhlmann’s (1907) recent work we find this 
observer dealt principally with G. fusca bred from pupae ; the flies 
being fed for the first time on calves, sheep and dogs infected with 
T. brucei. After 2 to 4 days, 80—90 °/ 0 of these flies developed a rich 
infection of flagellates in their alimentary tracts. Stuhlmann describes 
long forms which are found in the proventriculus and oesophagus but 
rarely in the proboscis; small forms which are almost exclusively found 
in the proboscis and seldom in the gut. He also describes amoeboid forms 
with or without flagella and regards them as resting parasites. Having 
studied these various forms Stuhlmann summarizes the development of 
T. brucei in G. fusca as follows: the cycle begins by a multiplication 
of indifferent forms in the intestine of the fly, the parasites then spread 
forward to the proventriculus where conjugation takes place, and as 
a result of this process small forms are produced which Stuhlmann 
believes are destined to pass into the vertebrate host. He was unable 
to find parasites in the end gut or any of the other organs. As a result 
of these observations on G. fusca bred from pupae and subsequently fed 
