214 BE. A. MINCHIN. 
but goes through a developmental cycle in G. fusca, ending 
with Herpetomonas-like forms, probably destined to infect 
vertebrate hosts. These results are entirely different from 
those obtained by me with T. gambiense in G. palpalis, 
where I found, without exception, that the trypanosomes did 
not survive after the fourth day, did not extend forwards 
into the proventriculus, and did not produce forms with » in 
front of N. As compared with T. grayi, the most note- 
worthy point of the development of T’. brucii is that the 
“ propagative” Herpetomonas-like forms occur only in 
the proboscis or most anterior part of the gut. In T. erayi, 
on the contrary, they are most abundant in the hindermost — 
part of the gut, where they may become encysted. This 
ifference between the two forms indicates that in T. brucii 
there is only probably inoculative infection, and no encyst- 
ment or contaminative infection. 
From the results, therefore, both of experiment and 
observation, 1t seems to me proved that 'I. brucii goes 
through a true developmental cycle in at least one species of 
the tsetse-flies that are agents in its transmission. Why, then, 
his lack of acquaintance with the habits and life-history of tsetse-flies—a 
knowledge only to be acquired, of course, in Africa. From my own experience, 
I agree thoroughly with Stuhlmann (41, p. 44) that Glossina lives exclu- 
sively on blood and contains in its gut only organisms taken up with blood or 
derived from its mother. Our experience is that Glossina is a most greedy 
and rapacious bloodsucker; we have seen it feed readily on frogs, lizards, 
snakes, chameleons, crocodiles (compare Koch [21], p. iv), and birds, as well 
as mammals. On one occasion, a chameleon put into a fly-cage was at once 
attacked by them, and, being unable to defend itself, was so bitten that it died 
in twenty minutes from loss of blood. We also made many attempts to feed 
isetses in other ways than with blood, but always without result (compare 
Stuhlmann, loc. cit., p. 44). On the other hand, there is not the slightest 
evidence that the tsetse can inherit trypanosomes from its parents (compare 
Stuhlmann, loc. cit., p. 70). Dutton, Todd, and Hannington (p. 202) bint 
at this possibility, solely from the far-fetched analogy of Piroplasma in 
ticks ; but in this case it is known that the mother-tick passes on to each of 
her offspring a supply of undigested blood containing the stages of the para- 
site. It is not necessary to point out that Glossina differs totally in both 
habits and life-history from either ticks or mosquitoes. 
