4&7 
among other forms to be described later, differ not only in degree but 
also in kind from those obtained on the one hand by Schaudinn, and 
on the other by Prowazek. The descriptions of Schaudinn, in so far 
as they bear at all upon the present work, do so, however, through the 
investigations of Trypanosoma noctuce , which since it appears to be a 
form of trypanosome requiring more than one host for the completion 
of its life cycle, may very likely differ in the features of this life cycle 
from the more ordinary forms with which we have been concerned. 
On the other hand, Prowazek’s results obtained in the case of Nagano. 
(that is to say, from one of the trypanosomes considered in the present 
paper), so far as the nuclear changes during fission are concerned, 
differ entirely from our own ; these latter fall directly into line with 
the observations we have made upon other forms, and are quite 
incompatible with the description of this process given by Prowazek in 
the case of T. lewisi or T. brucei. The question which now confronts 
us is upon what cause this difference of results depends. We are 
inclined to think that the difference of result is due to the methods 
which have been employed. We may as well say here, that from 
what we have gathered with respect to the different methods that 
have been generally in use, it appears that all the methods involving 
the drying of the blood before staining, or, in fact, any method 
involving drying at all, is, so far as nuclei are concerned, absolutely 
useless from a cytological point of view. Nothing relating to the 
delicate mechanism of mitotic division is generally preserved in cells, 
whether they belong to unicellular or multicellular organisms, when 
dried and stained with Romanowsky, Giemsa, or in any other manner. 
Even the resting nucleus itself under such conditions becomes a mere 
caricature of the actual structure. 
When treated in this way, the irregular or regular blotches and 
streaks of stainable matter have nothing in common with, and do not 
represent, even in a relative or equivalent sense, the structures actually 
present in the cells. Anyone who wishes to verify this fact for 
himself will have no trouble in doing so if, for example, he makes a 
smear preparation from the testis of a rat, stains after the manner of 
Romanowsky, and then compares this with a properly fixed and 
stained smear, in the production of which ordinary cytological 
precautions have been observed. It is a curious fact that in a rats 
testes under these conditions certain cells which really contain 
