144 



GENERAL BIOLOGY 



of the tsetse fly (glossina palpalis), and where this insect exists the dis- 

 ease is liable to prevail. The fly lives on the bushes on the lake shores 

 or river banks, and feeds on the blood of crocodiles, antelopes, etc. The 

 trypanosomes undergo changes in the body of the fly and the infectivity 

 does not appear until the thirty-second day, but continues for at least 

 seventy-five days." 



The parasite is found mostly in the cerebro-spinal fluid, though 

 less commonly in the blood. Hope of exterminating the disease seems 

 to lie in exterminating the game (crocodiles especially) on which the 

 tsetse fly feeds. 



FLAGELLATES OF UNCERTAIN POSITION. (Fig. 58.; 



12 34 



* 



6 7 



Fig, 58. 



Kala-Azar organism. 1, from a patient in India; 2 and 3, individual flagellate, 

 (Leishmania Jonovani) ; 4, 5, 6 and 7, Lcishmania infantum. (From Kolle- 

 Wassermann). 



Leishmania donovani. 

 Leishmania infantum. 

 Leishmania tropica. 



Causes Indian Kala Azar (dum-dum fever), Infantile Kala 

 Azar, and tropical boil, respectively. Common in Asia. Causes lesions 

 on exposed surfaces of body and enlarged spleen and anaemia. 



The bed-bug or a blood-sucking bug is 

 probably the common carrier because ingested para- 

 sites undergoing development into flagellate forms 

 have been found in the bed-bug. 



The infantile disease affects children only : 

 probably through dog fleas, as dogs are spontane- 

 ously infected in the epidermic regions. 

 Class IV. Infusoria 



Balantidium coli (or Entamoeba coli;. 

 (Fig. 59.) 



A ciliated, oval-shaped infusorian. There 

 is a "bean-shaped macro-nucleus and a spherical 

 micro-nucleus. In tissues the organisms frequently 



Fig. 59. 



Balantidium coli, from 

 an ulcer of man's intes- 

 tine. After Braun and 

 Luhe.) 



