8 
Rabinowitscli and Kempner were the first to employ white rats inoc- 
ulated intraperitoneally for the study of development, and they were 
able to trace the entire cycle of development by the examination at 
short intervals of the blood of a white rat so infected. By a similar 
examination of a great many rats we were able to get all the forms of 
development. 
Multiplication hy transverse division. — The first thing to be observed 
is a change in the outlines of the trypanosome. Its sharp beak becomes 
blunt; the flagellate end is no longer sharp, but rounded; the slender 
body becomes thickened and swollen ; both the longitudinal and the 
transverse diameters of the parasite are increased. There is a multi- 
plication of nuclei and centrosomes to a number which seldom exceeds 
five each, and they are arranged in a line parallel to the long axis of 
the parent trypanosome. After the division of nuclei and centrosomes, 
the next step is the formation of the new flagella, each of which takes 
its origin in a centrosome and generally emerges from the parent try- 
panosome on the side which bears the undulating membrane (PI. Ill, 
fig. 9). These new flagella gradually attain full length. The old fla- 
gellum becomes destro3^ed and disappears. The cleavage of the pro- 
toplasm of the parent occurs along lines at right angles to the long 
axis, so that each new segment of protoplasm is equipped with a 
nucleus, a centrosome, and a flagellum. 
The daughter cells are soon free in the blood and are readily dis- 
tinguished from the adults b}^ their small size and oval outliue. The}% 
however, gradually lengthen out into the familiar picture of the adult. 
MidUplication hy longitudinal division. — This form of multiplication 
has much in common with the transverse division. There is the same 
change in outline of the jDarent and the same multiplication of cen- 
trosomes and nuclei to a number of from two to six. The arrange- 
ment of the latter, instead of being in a line parallel to the long axis 
of the parent, is in a transverse line. The new flagella next appear. 
They arise at the front end of the parent and are arranged closely 
about the old flagellum and correspond in number to the centrosomes. 
(PI. I, fig. 3.) Rabinowitsch and Keni]3ner, in speaking of the origin 
of the new flagella, mention that in the flagellata the formation of the 
new flagella takes place so rapidly that the investigators can not fol- 
low the process accurately in all its details. They do not hold to the 
view that flagella multiply by a cleavage in the long axis of the old 
flagellum. It is their opinion that the new flagella arise from the 
body plasma and their principal support for such an origin is that in 
transverse division the new formation of flagella does not occur at 
the end close about the old flagellum, but on the side at a consider- 
able distance away from the old flagellum. 
MidUplication hy segmentation. — These three forms of division are 
separated only for description. They may all be seen side by side in 
the same preparation and in some instances the distinction between 
them is not altogether clear, especiallj^ between the longitudinal and 
