W. S. Patton 
141 
us to be the probable solutions of Kleine and Bruce’s work, and at 
present we are inclined to consider the last explanation as the most 
likely one. 
It can be readily understood that any multiplication forms of 
T. gambiense may be quite easily missed, especially when we consider 
that G. palpalis is nearly always infected with G. grayi and G. tullochi. 
This would at once explain why previous observers have failed to find 
T. gambiense in this fly several days after it has fed on infected blood. 
The multiplication forms of T. gambiense are not even known and the close 
similarity of the crithidia to trypanosomes would obviously lead to great 
confusion unless the life cycles of these natural flagellates are first 
carefully worked out. 
Up till the present it has been generally believed that T. gambiense is 
transmitted mechanically, that is to say the trypanosomes which remain 
in the fly’s proboscis are inoculated into a fresh host just as if they had 
been injected with a hypodermic needle. This method of infection must 
however be the exception, as the majority of the trypanosomes are 
undoubtedly taken into the stomach of the fly, and some time must 
necessarily elapse before they can find their way back again to its pro¬ 
boscis ; there is no evidence to show that during this period the trypano¬ 
somes pass through a sexual cycle. We would again point out that 
G. palpalis is known to be frequently infected with two natural flagel¬ 
lates, and that unless their life-cycles are completely worked out it will 
be impossible, even with bred flies, to study the changes T. gambiense 
undergoes in G. palpalis. 
The next paper is a preliminary communication by Chagas (1909) 
who describes two new trypanosomes, one T. minasense from a monkey 
Hapale penicillata, and the other T. cruzi from a bug ( Conorrhinus ). 
The non-flagellate stages of T. minasense are found in the lungs of in¬ 
fected monkeys; each parasite, according to Chagas, contains eight small 
organisms each provided with a bilobed nucleus; on their separating 
they penetrate the red blood corpuscles and become typical trypanosomes. 
Chagas considers this represents the process of schizogony. Six to eight 
hours after a bug ( Conorrhinus) has fed on an infected monkey the 
trypanosomes ( T. cruzil) in its stomach lose their undulating membrane 
and flagellum; the indifferent forms then multiply and cysts appear 
which Chagas considers represent a form of sexual development. In the 
proctodaeum of the bug crithidia-like forms were found in large 
numbers. Adult parasites resembling full grown trypanosomes were seen 
in the body cavity of the bug. It is not quite clear as to whether the 
