200 
infected rats by means of the rat louse, and consequently we had in 
this form of trypanosome a convenient object for investigating the 
changes which might take place among the trypanosomes when in 
the body of the louse, which here forms an intermediate host. 
Passing now to the features of the developmental cycle in the 
parasites T. gambiense and T. Icwisi in the blood, we find in the case 
of T. gambiense* injected into rats that the disease is marked by 
alternating phases of presence and absence of parasites in the 
peripheral circulation. If numerous preparations be made of the 
blood at short intervals during the whole course of the infection, it 
is found that at the time the parasites are increasing in number in 
the blood, rapid multiplication is going forward by means of 
longitudinal fission. Such fission is accompanied by amitotic division 
of the nucleus and the intra-nuclear centrosome (nucleolus, 
karyosome), as well as by amitotic division of the extra-nudear 
centrosome (blepharoplast), and lastly by the development of a new 
flagellum, and the final splitting of the original trypanosome into Ho 
separate flagellated cells, each containing a nucleus, an intra-nuclear 
centrosome, an extra-nuclear centrosome, and a flagellum. 
Apart from the form of multiplication to which we have referred, 
no ot er form of reproduction takes place during the increase in the 
um er of the parasites in the blood, and when we reach a point at 
or near the maximum number of trypanosomes in the circulation, the 
parasites cease to divide. At such periods it is found that in large 
rentrn ^ ^ T^ stainablc band develops from the extra-nuclear 
with extends, and finally becomes connected 
to the^H ^^^1 breaks up and disappears. Subsequent 
II n the trypanosomes 
tmainTd A “ ^ ^ has not bee. 
number of th infection where the 
ra;::^ changes a^e uUmJ" 
become more compact ves^T ‘rypanosomes. The nude, 
nuclei, together with the elation to them, and the 
portion of the cell and '’T n separated from the outer 
The remainder of’such ccIL ' J- "" 
body consisting of the nu^ ! 
-—- - —__ nucleus, the vesicle, and a covering of 
• Salvin-Moore and Breinl, /oc. at. 
