9 
transverse modes. Division bj' segmentation begins with a curving 
of the i^arasite which continues until the two ends approach each 
other and finally meet, thus giving the parasite a globular form. The 
fiagellum becomes lost and the undulating membrane disappears. 
The nuclear multiplication now occurs and proceeds in the same man- 
ner as in the longitudinal and transverse division. The nucleus 
becomes swollen, appears coarsely granular, and divides into two 
parts, each of which probably divides and subdivides. 
In stained preparations Rabinowitsch and Kempner saw small 
bodies in the new nuclei. These bodies, which were about the size of 
centrosomes, took the stain deeply and were placed at the periphery 
of the nucleus. Whether centrosomes can arise from nuclei or onlv 
t/ 
from other centrosomes is a point of controversy and is mentioned 
under morphology. 
Whatever may be the source of the centrosomes their number 
always keeps pace with the number of nuclei. Xo matter how many 
are formed there is a formation of a corresponding number of centro- 
somes until in the end there are as many centrosomes as nuclei in the 
trypanosome. 
As regards the manner of the arrangement of nuclei and centro- 
somes in the globular parent, we find them in two concentric circles. 
The outer circle contains the nuclei and the inner circle the centro- 
somes. In the cleavage of the protoplasm there are as many segments 
as number of nuclei. While in transverse and longitudinal di\usion 
there are not more than 6 daughter cells, we find in this form as many 
as 16. Plate III, figure 12, shows 14 segments. 
Cleavage proceeds from the j)eriphery to the center of the mass, so 
that a rosette arises as in the segmentation of malaria. Each segment 
of protoplasm contains a centrosome and a nucleus, and a fiagellum 
develops from each. In hanging dro]3 these rosettes are seen to be in 
agitation as soon as they acquire their flagella. Finally the segmen- 
tation is complete and the daughter trypanosomes are seen as small 
oval 3 'oung forms free in the blood. Rabinowitsch and Kempner, in 
speaking of segmentation, refer to the hanging together of the young 
by their sharpened ends and their gradual separation from each other; 
but the}’ maintain that the young parasites may develop into adults 
before the radial arrangement is broken up, as is shown in their figure 
27 (Rabinowitsch and Kempner, 1899, pi. 3, fig. 27.) We have not 
seen them develop into adults while so arranged. The rosettes seem 
to become dissolved while their members are still young. W e should 
think that figure 27 represented an autoagglutination of adults rather 
than an advanced stage of a rosette, for the reason that the members 
are evidently adults instead of young forms. 
THE DURATION OF THE INFECTION. 
Rabinowitsch and Kempner found that artificially infected white 
rats harbor these parasites in general from four to six weeks. They 
