1908.] 



A Trypanosome from Zanzibar. 



19 



round, or rod-shaped, and is situated close to the posterior extremity. It 

 stains more deeply than the nucleus. 



Undulating Membrane. — The undulating membrane is narrow. As a rule 

 it is straight and simple, and does not show much tendency to be thrown 

 into folds. 



Flagellum. — The flagellum stains intensely. It is well marked, and does 

 not project beyond the protoplasm of the cell and the undulating membrane. 

 Sometimes, in faintly-stained specimens, there is the appearance of a slight 

 projection of the flagellum beyond the body ; but, speaking broadly, thi? 

 species of trypanosome may be said to have no free flagellum. 



The conclusion to be drawn from a study of the morphology of 

 Dr. Edington's trypanosome, Trypanosoma dimorphon, and Trypanosoma 

 ■congolense, is, that the two first resemble each other very closely, whereas 

 Trypanosoma congolense seems to be of a somewhat shorter and stouter form. 

 It will also be seen that in the strain of Trypanosoma dimorphon used there 

 is only one form, and that, the short or tadpole form described by Dutton and 

 Todd. With regard to this, it may be of interest to quote some remarks of 

 Dr. Breinl, to whom I am obliged for his courtesy in sending me this strain. 

 He writes : — " With regard to Trypanosoma dimorphon, you are aware that 

 some remarkable change has occurred in the strain between the time 

 Drs. Dutton and Todd brought it back from Africa and we started work 

 on it here. Whereas Drs. Dutton and Todd describe the long flagellated 

 forms with the free flagella, Thomas and myself, Laveran and Mesnil, could 

 not see these forms with a thin body and a long flagellum. The strain I send 

 you in a rat is the original strain." 



It is difficult to understand how this change in morphology has been 

 brought about. It may be that Dutton and Todd were dealing with a double 

 infection, of which one has died out. This point will require to be investi- 

 gated on the spot. 



Another matter for consideration is whether this name Trypanosoma 

 dimorphon should be adhered to. It certainly seems a misnomer when 

 applied to the strain figured above. If it should be decided to drop it, 

 I think the compliment should be paid to Dr. Todd of naming it after him. 



Inoculation Uxperiments on various Species of Animals. 



The animals, in which the effect of the inoculation of Dr. Edington's 

 trypanosome has been studied, have been horses, cattle, goats, monkeys, dogs, 

 rabbits, guinea-pigs, white rats and mice. The inoculations were made, as a 

 rule, intraperitoneally. Inoculation experiments with Trypanosoma dimorphon 

 are also given for purposes of comparison. These are printed in italics : — 



c 2 



