OCCURRENCE OF NUCLEAR DIMORPHISM IN HALTERIDIUM, 345 
siderable importance (text-fig. 7). This is in a smear, well 
fixed and well stained, which was made from heart-blood and 
smeared straightway. The parasite is not altered or de- 
formed in any way mechanically; I am confident that it 
represents a normal phase. The individual in question is 
free in the blood. It is of the indifferent type, and the two 
nuclei are in close contact, both dense and deeply staining. 
The pigment grains are all near one end of the cytoplasm, in 
Text-Fie. 11. 
Large Trypanosome, from peripheral blood. x 2500. 
a position in which they might easily be got rid of. The 
most interesting point is the presence of an unmistakable 
thread or line, which is stained bright red. This starts from 
a short, transverse, deep-staining band, adjoining the two 
nuclei, and runs down part of the length of the body near to 
one side, terminating in a definite granule. The narrow 
portion of the cytoplasm between it and the margin of the 
body has a distinctly reddish tinge, the rest of the protoplasm 
being of the usual blue colour. The only explanation I can 
give of this thread is that it represents the ‘central spindle”’ 
