292 Prof. J. E. Salvin Moore and Mr. A. Breinl. [Mar. 9, 
been reached, the parasites in the blood rapidly diminish in number, and 
during the period of diminution large numbers of trypanosomes may be 
encountered in the lungs, the spleen, and the bone-marrow (but at the same 
time also in the blood), wherein a profound and rapid change is taking place. 
The nucleus becomes more compact (see Diagram I, c). There arises a vesicle 
in connection with it, and eventually a complex structure (latent body) is 
produced,* consisting of the nucleus and vesicle, and enclosed by a delicate 
covering of cytoplasm. The latent body becomes detached from the rest of 
the protoplasm of the cell, and the whole remaining portions of the trypano- 
some now rapidly degenerate and disappear, so that in a short time we find 
nothing but numbers of the complex spherical latent bodies remaining. 
These eventually become chiefly lodged in the spleen, the bone-marrow, and 
other organs. The process we have just described, or, at least, parts of it, 
have undoubtedly been seen in other trypanosomes, but not in Gambiense, 
by various observers, and they have generally been interpreted as a form of 
degeneration. That this is not necessarily so seems now, however, to have 
become clearly demonstrated. In the case of 7’. gambiense we were able to 
find, during the period when no parasites were present in the blood, that 
the latent bodies still persisted in the organs, and that many of these 
gradually grew larger by developing a cytoplasmic investment, a new extra- 
nuclear centrosome, and afterwards a flagellum, such forms returning 
eventually to the form of ordinary trypanosomes. 
We have thus in the case of the sleeping sickness parasite a cyclical meta- 
morphosis going on in the blood of the infected animal. The parasites pass 
through divisions until the interaction between the extra-nuclear centrosomes 
and the nucleus. From this period they proceed to the formation of latent 
bodies, and subsequently to the development from the latent bodies of 
ordinary trypanosomes once more. | 
The interaction between the nuclei and the extra-nuclear centrosome 
(blepharoplast) may, as we have pointed out,} suggest a novel form of sexual 
process, and the whole series of changes may indicate that the life-cycle of 
T. gambiense is in reality completed in the body of the rat or man, and not 
necessarily related to the transference of the parasites to any other form of 
host. We know, however, that in the form 7. gambiense the parasites can 
be transmitted by the fly Glossina palpalts. 
The observations of Schaudinn apparently indicate that in the case of 
Trypanosoma noctue the sexual stage (which is described by him as quite 
unlike the process to which we have just drawn attention) occurs in the body 
* Salvin Moore and Breinl, loc. cz. 
+ Salvin Moore and Breinl, loc. cit. 
