468 
sixteen gemim or heterotype chromosomes, when subject to the 
action of drying and Romanowsky, very often present (within the ill- 
formed area representing the nucleus) six irregular masses of 
stainable stuff resembling the so-called chromosomes of the dned 
trypanosomes. Such appearances are, however, certainly due to 
regularity of coagulation and shrinking during the drying of the cells, 
and have nothing in common with the real morphological structures, 
(the chromosomes), which either the living cells, or successfully- 
preserved cells possess. In view of these circumstances, we are 
inclined to regard many accounts of the existence of chromosomes, 
spindles, and even the assumed existence of mitotic division among 
trypanosomes, as conclusions which appear to be most questionable, 
and as requiring in all cases confirmation in a variety of ways which 
do not involve the violence dealt to the finer details of cell structure 
by drying. 
Finally, we see in the case of 7 rypanosoma gambiense that the 
life history of this parasite as it lives in rats seems to be complete in 
the blood of the rat, and not in any way dependent for its completion 
upon the transference of the parasites into the blood of any other 
kind of host. In rats the latent forms pass gradually into trypano¬ 
somes, these m turn divide through many generations, and their 
multiplication is followed by a metamorphosis which, whether we 
regard it as a special form of sexual process, as a form of patho¬ 
genesis or as a sexual stage, the fuller details of which have not yet 
been elucidated, seems undoubtedly to stand in one of these 
relationships to the normal cell multiplications preceding the 
formation of latent bod.es. The stage in quest,on results In the 
production of the latent bod.es once more, and the cycle is complete, 
cvcl c r y , l ° thiS COnce P tl0 " ‘hat, notwithstanding the 
a isMhv Pment tt; yPanOSOma SamHe "* C - Stl " there may exist 
P r0bab 'hty. of the transference of the trypanosomes 
e X u“Z P 7,u° St Wheie a further metamorphosis representing the 
be SO the ° rgan,5ms ls P“-d through. Tins, of course, may 
mstalce of a ^ ““ ° f the ^ypanosome of Dour.ne a clear 
r.fnt^TT 1 '" hiSt0ry ' " hlch ' ™der norma, circun.- 
norma^uc:^"^ ' n ‘° of host; and, under 
whatever sexual stap-e ** >,OSOma e V ul perdu m must pass through 
sexual stage ,t may possess, its whole life h.story m fact, in 
