MASTIGOPHORA 413 



are found as trypanosomes in the blood plasma. Slender and 

 thick forms occur here, the difference probably depending upon 

 the age of the parasites. 



Monkeys, rats, mice, young guinea-pigs and many other 

 mammals are suceptible to inoculation. The infection is tran- 

 mitted by a bug, Cdnorhinus megistus, in which the protozoon 

 develops abundantly. The bedbug, Culex lectularius, also is 

 capable of transmitting the disease. 



Cultures are readily obtained 

 on blood-agar and Chagas was able 

 to infect animals with such cultures. 



Leishmania Bonovani. — Lav- ^^^^ 



eran and Mesnil in 1903 described %^^S \ 

 this protozoon which occurs inside ^*^ 

 cells in various parts of the body, ^'°- i^g.—Schizotrypanum cruzi 



. • 11 in human blood. {From Doflein 



but IS especially abundant m the after Chagas.) 

 spleen and liver, in the disease 



known in India as Kala-Azar or tropical splenomegaly. The 

 organism is oval, 2 to 4/* in diameter, finely granular and some- 

 times vacuolated. In the interior there is a large rounded nucleus 

 and a smaller oval or rod-shaped blepharoplast, near which a third 

 very slender short thread may usually be recognized as the rudi- 

 ment of the undeveloped flagellum. These structures are doubled 

 in the division stages. Multiple division also occurs. In the cir- 

 culating blood the organism is found within lymphocytes and poly- 

 nuclear leukocytes. Many of them may be found in a single cell. 



Cultures are readily obtained by inoculating fluid (citrated) 

 blood with blood or with spleen juice containing the parasites, or 

 by inoculating the usual blood-agar. In artificial culture the 

 cell elongates, the rudimentary whip extends into a true flagellum 

 and the organism assumes the appearance of a typical leptomonas 

 (herpetomonas). Little difficulty is experienced in keeping the 

 cultures alive and flourishing. 



The parasite has been supposed to be transmitted from man 

 to man by bugs of the genus Cimex, but this hypothesis has been 



