THE STRUCTURE OF TRYPANOSOMA LEWISI. 805 
stain the intra-nuclear substance appears a pale red tint, and 
does not show granulations (Pl. 25); with methylene-blue- 
eosin it is pale blue. In the standard preparations stained 
with methyl-green no granulations are to be made out in the 
nucleus, which has simply the appearance of an oval vesicle, 
in which the distinct karyosome is suspended (figs. 1-8). 
From all these various appearances | conclude that the 
intra-nuclear space contains, probably, in the living condition 
a more or less fluid nuclear sap, in which chromatin is sus- 
pended in the form of particles, perhaps differing in size or 
in concentration of substance, but for the most part too minute 
to be resolved with the microscope, except when very deeply 
stained, or artificially enlarged by the deposit of the stain 
round them. 
In the foregoing paragraphs I have dealt with the minute 
structure of the trophonucleus; I will now mention some of 
its variations as a whole. In the first place it varies con- 
siderably in size, as may be seen from my figures. There 
may sometimes, moreover, be two trophonuclei present, flat- 
tened against each other and each of relatively small size (figs. 
6, 84). This condition, which is found ina very small number 
of the trypanosomes, does not appear to have anything what- 
ever to do with division, as all other parts of the body are in 
the normal single condition; I regard it simply as an abnor- 
mality. In rare cases trypanosomes are met with having 
three trophonuclei (fig. 74). 
In preparations fixed with Flemming’s fluid (figs. 56-38) 
and Hermann’s fluid (figs. 40-44) the trophonucleus often 
seems to float in a space in the cytoplasm, a condition which 
must be regarded as an artefact. 
In this memoir I have only dealt with the structure of Try- 
panosoma Jewisi in the resting, “adult” stage. It is my 
hope im a future memoir to extend these studies to the multi- 
plication-period, and possibly to other developmental periods 
of the life-history. 
LisTER INSTITUTE, 
January, 1909. 
