238 ANIMAL PARASITES 



Trypanosoma equiperdum causes a sexual disease in stallions 

 and mares called dourine; this is akin to syphilis in man. 



Trypanosoma lewisi of rats is transmitted from animal to 

 animal by means of fleas. 



Trypanosoma noctuae. A parasite of the little owl, which is 

 introduced into the bird through the bite of the mosquito Culex 

 pipiens. 



Several other forms have been noted but these are perhaps 

 the most important and serve as examples for this family of 

 protozoa. 



Trypanosomes are elongated fusiform bodies pointed at both 

 ends, provided by a fin fold, or undulating membrane, running 

 along the dorsal edge and forming frill-like folds which terminate 

 in a whip-like extremity or flagellum. 



A large nucleus is always seen, also a centrosome, a small chro- 

 matic mass likewise called a blepharoplast near one pole. 



The flagellum is at the anterior extremity; the blunt pointed 

 end is the posterior extremity. Cell division begins in the bleph- 

 aroplast, the cell dividing longitudinally, the nucleus, flagellum, 

 and the protoplasm dividing last. Dividing trypanosomes fre- 

 quently appear in clumps with the ends. united, resembling a 

 wheel. 



The trypanosomes exist in two hosts one a suctorial insect 

 and have a sexual and an asexual existence (alternate generation). 

 In an infected owl the organism has been observed clinging fast 

 to the red cells, absorbing nutriment during the day, while at 

 night it swims about freely in the plasma. 



In owl's blood the trypanosome assumes asexual forms, called 

 macro gametes. These macrogametes penetrate the erythrocytes, 

 accumulating the remnants of the red cells in the protoplasm. 

 The nucleus of the trypanosome^ may be seen in the interior of 

 the protoplasm. The microgametocytes arise from the asexual 

 forms and when mature, give rise to eight microgametes. 



