674 MURIEL ROBERTSON. 
part of the body at the extreme anterior end (flagellate end) 
projects—this is, as far as I could make out, not withdrawn 
into the body, but seems like the membrane and flagellum to 
disintegrate. After a time the nucleus becomes quite indis- 
tinct, and I noticed that after this I was never able to get a 
very clear view of the nucleus until just before the flagellate 
condition was again adopted, when it showed with customary 
distinctness. Furrows now begin to appear in the animal, 
and it divides into two (text-fig. 3, 4 and s). Another division 
TEXT-F1IG. 3.—Stages in the crop of the leech. A and B. 
Division stage of one individual. cand p. Individual adopt- 
ing the pear shape at time of division. &. Newly-rounded off 
Trypanosome with flagellum still attached. 
follows this, and four irregular rounded or pear-shaped crea- 
tures are thus formed, lying generally more or less connected. 
They now put out each a flagellum on one end. The flagellum is 
at first simply a short thick process. It lengthens and begins 
to lash slowly from side to side, but is as yet not capable of 
moving the body. Presently a slight oscillation of the body 
of the parasite is to be observed, and ultimately as the 
flagellum lengthens the creature becomes motile. 
