LEISHMANIA TROPICA 



379 



on the agar at 20° to 22° C, producing flagellate and division forms 

 on the fourth day, which increased in numbers by the eighth to tenth 

 day, when rosettes appeared and increased in such numbers that the 

 masses were visible to the naked eye. After this a tendency to 

 agglutination develops and increases until after one or two months 

 the parasites die. The typical flagellate of these cultures is herpe- 

 tomad-like, measuring with the flagellum 40 to 45 fj,, with a breadth of 

 2 to 4 but the flagellum alone measures 16 to 20 fi. There is no 

 undulating membrane, but a trophonucleus and kinetonucleus can 

 be seen. Three types of flagellates can be seen in cultures- — viz., 

 one almost spherical, a second short and stumpy, and a third long 

 and narrow. Subcultures are best made from the tenth to the 

 fifteenth day, and these can be repeated apparently indefinitely. 

 Forty-five generations have been recorded during aperiod of eighteen 

 months. 



It is usual to state that there are no differences between the 

 cultural forms of L. tropica and L. donovani, but Row considers 

 that there are several points of difference — viz., that the flagellate 

 forms of L. tropica are longer and larger, that the flagellum is 

 longer, while the growth is quicker and may take place at higher 

 temperatures than in L. donovani. 



Inoculation. — Martzinowsky, Wenyon, and Patton have success- 

 fully inoculated themselves, and other people have also been suc- 

 cessfully inoculated from cases of Oriental sore. The incubation 

 period varies from sixteen days to six and a half months, and the 

 papule is generally ushered in with febrile symptoms lasting several 

 days. The inoculated sore begins as a papule, and becomes a 

 nodule; when excised and examined it presents the typical ap- 

 pearances of Oriental sore, and contains L. tropica. 



Successful inoculations are recorded from man to monkeys and 

 dogs, from monkeys to man, other monkeys and dogs, from dogs 

 to dogs, and from cultures to man, monkeys, and dogs. 



Immunity.^ — Infection confers immunity if the cure is complete, 

 and if a sufficient interval has elapsed between the cure and the 

 reinfection; if not, a condition of hypersensibility is produced, as 

 demonstrated by a shortened incubation period. Kala-azar infec- 

 tion ii! dogs affords immunity against L. tropica during and after the 

 attack; Oriental sore protects monke^^s partially or completely 

 against L. donovani. 



Insect Carriers.- — -No insect at present has been demonstrated to 

 be the true host of L. tropica. Musca domestica may possibly be a 

 carrier because the parasites can retain their vitality therein, and 

 may be transferred to any raw surface, and thus induce infection; 

 but it is not a true host, though Row has found the contents of the 

 gut to be infective, and believes that infection can be spread by its 

 faeces. There can be no doubt that a natural culture producing 

 flagellates and, according to Patton, even post-flagellate forms, can 

 take place in the bed-bug Clinocoris rotundatus, but all attempts at 

 transmission have failed, and the same condition of affairs holds 



