202 Mutati07i in Micro- Organisms 



The Trypanosomes are Protozoa possessing a very remarkable 

 structure. It is necessary, therefore, to recall at the outset the 

 structures present in a typical animal of this sort. This can be 

 most clearly done with the aid of a diagram (Fig. A), an inspection 



Fig. A. Structure of a typical Trypanosome. 



(1) Trophonucleus, or chief nucleus. (2) Kinetonucleus, or smaller nucleus, in connexiou 

 with locomotory apparatus. (3) Blepharoplast — a minute basal granule at the root 

 of the flagellum. (4) Undulating membrane, used in locomotion. (5) and (6) Flagel- 

 lum — marginal (to undulating membrane) and free parts. Ant., anterior or flagellar 

 end. Post., posterior or aflagellar end of organism. 



of which will, I think, make further explanation unnecessary. The 

 terminology of the parts is that of Minchin. To avoid any confusion 

 I should mention that the organ which is called kinetonucleus through- 

 out this paper is called centrosome by Laveran, and blepharoplast^ by 

 the majority of German workers. It should also be added that Try- 

 panosomes reproduce by longitudinal division — both nuclei dividing 

 into two. 



I will now describe the curious structural changes which have been 

 brought about in certain Trypanosomes, and will begin with the work 

 of Wendelstadt and Fellmer (1910). 



It has been found by these workers that Trypanosomes — they used 

 two species, Trypanosoma brucei and T. lewisi — which normally live in 

 the blood of certain mammals {e.g. rats) may be inoculated into cold- 

 blooded vertebrates and invertebrates, in which they can live for a 

 certain time. The Trypanosomes used were from well-known strains 

 which had been cultivated in rats and under observation in the 

 laboratory for several years. 



Trypanosoma brucei was, after some difficulty, passed from the 

 blood of rats into the blood of grass snakes {Tropidonotus natriwy. 

 In the snake's blood, the Trypanosomes become smaller (Fig. B, 2), 

 as compared with the initial forms in the blood of the rat (Fig. B, 1). 



1 Frequently — and incorrectly — also written " blepharoblast." 



' The authors refer to the snake merely as the " Eingelnatter," but presumably this 

 animal is meant. 



