776 E. A. MINCHIN. 
fixed in the same manner, namely by osmic vapour followed by 
absolute alcohol, without drying at any time; a (figs. 64-69) 
and } (figs. 62, 63) were stained with Giemsa’s stain, and 
passed through acetone and xylolinto Canada-balsam ; ¢ (figs. 
10, 11) was stained with iron-hematoxylin and mounted in 
the ordinary way. 
In preparation b (figs. 62, 63) the passage through the 
acetone was evidently effected without any extraction of the 
stain taking place ; the trypanosomes are perfectly similar in 
general appearance to those stained with Giemsa and dried 
off (figs. 60, 61). In preparation a (figs. 64-69), on the other 
hand, a considerable amount of extraction has taken place, 
which, however, is different in degree in different parts of 
the preparation; in one place a clump of trypanosomes may 
be found, all showing a deeply stained, opaque red tropho- 
nucleus ; another patch of trypanosomes will show the stam 
greatly extracted. Hence in this preparation I have been 
able to find every stage of the extraction of the stain, and 
have put together the series shown in my figures. 
The series begins with trypanosomes, in which the tropho- 
nucleus differs only from those in preparation b by its smaller 
size (fig. 64), showing that the process of extraction begins 
by removing the stain deposited outside the nuclear mem- 
brane; at the same time the kinetonucleus is considerably 
diminished in size, the periplast-line begins to stand out, and 
the flagellum is thinner. In the next stage (fig. 65), the 
trophonucleus is pale with a few scattered coarse granulations, 
amongst which it is still difficult to identify the karyosome. 
In the next two figures (figs. 66, 67), it is seen that the 
coarse granulations are disappearing, leaving the karyosome 
standing out plainly, with a more or less distinct clearer space 
round it. In the last two figures (figs. 68, 69), which repre- 
sent the last stage of extraction and the condition that is 
most frequently met with in the preparation, the trophonucleus 
is reduced to an oval space of faint pink colour, in which the 
karyosome or karyosomes stand out sharp and clear—exactly 
the same state of things which is found in preparation ¢ 
