802 E. A. MINCHIN. 
to divide into two, and each half divides again ; two of the 
“‘ copulate,” 
four parts are thrown out, the other two parts 
and the nucleus is reconstituted. Kqually complicated pro- 
cesses are seen in reduction and parthenogenesis. 
For my part I am very doubtful if the different appearances 
seen in the nuclei of I’. lewisi will bear the excessive weight 
of subjective interpretation which Prowazek places upon them. 
Moreover, Prowazek seems to have based all this theoretical 
superstructure upon Romanowsky-stained preparations, which, 
in my opinion, are altogether false and misleading for minute 
nuclear structure. 
All that can be inferred from a comparison of different 
trypanosomes is that the karyosome sometimes gives off 
smaller portions; some of these go to the surface of the 
nucleus, and I think it highly probable that the chromatoid 
grains described above take origin in this way. 
The intra-nuclear chromatin shows different conditions 
according to the stain used and the degree of extraction of 
the stain. With iron-hematoxylin, for instance, the whole 
nucleus is at first a dense black patch, owing to the intra- 
nuclear chromatin being stained so deeply as to obscure 
completely the karyosome. A similar condition is seen after 
the Romanowsky stain. As the stain is extracted, the intra- 
nuclear chromatin gradually becomes lighter in tint, and the 
karyosome begins to stand out. The extraction of the 
colour from the intra-nuclear chromatin does not take place 
uniformly, however, but some of the granules retain the stain 
longer than others, while some parts become quickly decolor- 
ised ; there is very often a distinct clear halo round the 
karyosome (figs. 17, 18, 39). With complete extraction the 
intra-nuclear substance becomes pale and gives the impres- 
sion of an empty space, im which the karyosome is suspended 
(fig. 10, 11). A quite similar and parallel series of appear- 
ances is seen when the Romanowsky stain is slowly extracted, 
as described above, but in this case the granules in the intra- 
nuclear space are much larger, more of the nature of concre- 
tions, than they are after iron-hematoxylin. With Twort’s 
