UNIVERSITY OF CALIFORNIA PUBLICATIONS 



ZOOLOGY 



Vol.6, No. 6, pp. 127-144, Pis. 15-17, 1 text-figure December 24, 1909 



THE LIFE HISTORY OF TRYPANOSOMA 

 DIMORPHON, DUTTON & TODD. 



BY 



EDWARD HINDLE. 



GENERAL ACCOUNT. 



This species was discovered by Dutton and Todd (1903) in 

 1902, during their exploration of Senegambia for trypanoso- 

 miasis. They Hound the parasite occurring in the bl 1 of 



horses, in which it is the cause of a very fatal malady. The 

 si rain was brought back to the Liverpool School of Tropical 

 .Medicine on the return of the expedition, and has since been kept 

 going in the usual experimental animals, most of which are verj 

 susceptible to this trypanosome. Dutton and Todd (1903) 

 described the existence of three different forms of this parasite, 

 viz., "tadpole forms." found chiefly at the commencement of 

 infection; "stumpy forms." common during intermediate stages; 

 and "long forms." preponderating in the later stages of infec- 

 tion. They considered the first two types to differ merely in size, 

 thereby reducing the three categories to two, and accordingly 

 gave the specific name dimorphon. 



Laveran and Mesnil (1904), although on the whole agreeing 

 with Dutton and Todd's description, came to a different opinion 

 regarding the distinctness of the forms. They recognized the 

 existence of "stumpy forms" and ''long forms." denying the 

 existence of any free flagellum, however, in the latter, but re- 

 garded them as representing only one type because of the exist- 

 ence of intermediate stages between the two extremes. The 



