224 
Durrant an ^ Holmes (30) describe similar rounded forms in T. evanti, 
c atter described them as undergoing development. He also describes the second 
type of rounded trypanosome and its development as do Breinl and Moore. 
It is impossible to say how far this resemblance extends. At all 
events, the above observations prove that the spherical forms represent 
n stage in a definite cycle of development other than that of 
longitudinal division, the only definitely developmental phenomenon 
previously established in the life history of trypanosomes. The 
observations of Holmes, Moore and Breinl show that there is possibly 
a. third line of development in mammalian trypanosomes, in addition 
to the multiple segmentation first described in Trypanosoma lewisiT 
Some of the rounded forms of mammalian trypanosomes doubtless 
degenerate and die, as do similar forms of Trypanosoma loricatum. 
But this constitutes no reason for calling all rounded forms degenera¬ 
tive or involutive, as has been so frequently done. The greatest 
caution must be used in applying such terms ; it is chastening to 
remember that only ten years ago a flagellating malaria parasite was 
w idely believed to be a degenerating form! 
Conjugation* has not been seen certainly. Possibly it does not occur 
during multiplication in Trypanosoma loricatum by the swarm 
cycle; but it is not at all impossible that a union of sexually 
differentiated individuals may occur at some other period.! 
of a cycle (probably sexual) 
It has been stated that the 
occurrence 
ln niamm alian trypanosomes ingested by tsetse flies is inherently 
mprobable. The following are the points most usually cited 
support this view :_ 
(0 It is said that there is no need for a sexual cycle since 
trypanosomes may be transmitted for an indefinite pe«° d 
bites a ” ICa ^’ ^ rom an > n ial to animal by simple inoculation and b) ) 
(2) that the trypanosomes 
may be kept for very long periods 
wel 
diff 
sug 
