434 



TR YPA NO SO MI DM 



Microgamete. — The microgametocyte escapes from the capsule-like peri- 

 plast, and its nucleus breaks up into eight double chromosomes, which are 

 reduced to eight single chromosomes. These travel to the periphery, and 

 form microgametes in the manner described for Hcemoproteus noctucB, micro- 

 gametes wMch they are said to resemble. 



Macrogamete. — The macrogametocyte escapes from its enclosing cell, and 

 the process of development of the macrogamete is the same as in Hesmo- 

 proteus. 



Fertilization. — This is the same as in Hcsmoproteus. 



Ookinete. — There are the same three kinds of ookinetes as in Hcsmoproteus — 

 viz., the indiflerent, the male, the female. 



The ookinete, however, differs by growing in size and multiplication of its 

 nuclei, and at the same time coiling upon itself so as to form a skein. This 

 skein contains a large number of nuclei uniformly distributed. 



Around each of these, small portions of protoplasm gather, and become 

 finally separated off, to form small indifferent tr3rpanosomes in the case of 

 the indifferent ookinete, male trypanosomes from the male ookinete, female 

 trypanosomes from the female ookinete. A large mass of residual protoplasm 

 is left. 



These trypanosomes, especially the male, are very minute, and reproduce 

 by longitudinal division, during which they do not separate at once, but 

 remain attached posteriorly. Couples attached to one another may extend 

 into the same straight line, thus giving rise to a spirochaete-like form, and 

 while in this position may undergo longitudinal division. The spirochaete 

 forms may become pear-shaped resting forms. 



In the Owl. — On entering into the owl, the indifferent forms pass through 

 alternate endocellular and free stages. In the former there is growth, and 

 in the latter there is division into smaller forms. After some time micro- and 

 macro-gametocytes are formed in increasing numbers. 



This life-history has been doubted, but Sambon has seen forms in which 

 a coiled trypanosome body can be detected in the blood cells. 



The Enclosing Cell. — There has been great doubt as to the character of the 

 body enclosing a leucocytozoon. 



1. Ziemann, Schaudinn, Dutton, Todd, and Tobey believe that it is a 

 portion of the parasite itself — i.e., the periplast — and that it may enclose a 

 red blood cell. 



2. Danilewsky considers it to be a leucocyte, but derived his red cells from 

 leucocytes. In considering it to be a leucocyte, he is supported by Laveran, 

 Lucet, Sakharoff, and Berestneff, and most recent observers. 



3. Laveran in his earUer observations believes it to be a red cell, and this 

 Sambon supports, as do Keysselitz and Mayer. 



It may be taken to be a much-enlarged dehaemoglobinized hsematoblast 

 or red cell, the spindle shape of which may be explained by the fusiform 

 shape of the haematoblasts, and by the pseudopodia of the young parasites 

 protruding into the long ends of the host cell. When the parasite contracts, 

 these ends shrivel up, giving rise to the usual appearance. 



The Spirochsetes. — At first Schaudinn, after tracing out the life-history 

 described above, thought that all spirochaetes would be found to- be allied to 

 true trypanosomes; but in 1905 he stated that the spirochaete-like forms which 

 he found in the little owl were far removed from true spirochaetes, and that 

 the relationship was only phylogenetic, and very distant at that. 



E. H. Ross has brought evidence to show that Kurloff's bodies [i.e., 

 clear spherical vacuoles in the large lymphocytes of guinea-pigs) are 

 intracorpuscular stages in the life-history of a Leucocytozoon {Lymphocyto- 

 zoon cohaycB E. H. Ross, 19 12) which ultimately give rise to spirochaete-like 

 bodies, the development of which he traces, and which he considers to be 

 the gametes. Later he and McDonagh described a similar origin for Treponema 

 pallidum. 



Recent work has tended to confirm the doubts thrown on Schaudinn's 

 work, but the general appearance of a Leucocytozoon in its cell is sometimes 

 remarkably similar to a trypanosome. It is possible that there may be 



