DISEASES PRODUCED BY TRYPANOSOMATA. 427 



probabl}' the best. Trypanosomata stained by this method show a fish- 

 shaped body, the front end of which carries a flagellum. The body of 

 the trypanosoma is coloured blue. At the anterior end may be seen a 

 red- stained nucleus ; at the opposite end a much smaller red spot, which 

 has been termed the nucleolus, but is more properly described as the 

 centrosome. From the centrosome a red thread extends along the outer 

 margin of the body as far as the front extremity, where it becomes 

 continuous with the flagellum. 



The trypanosomata increase by longitudinal fission. The centrosome 

 and then the nucleus divide, and finally a second flagellum is formed. 

 Sometimes the young trypanosomata remain connected, producing the 

 so-called " rosettes." 



The disturbance produced by trypanosomata seldom becomes acute, 

 but often continues for years. The only sign of disease consists in ill- 

 defined fever with long intermissions. The destruction of the red blood 

 corpuscles causes anemia, the animals or men become weak and waste 

 away, oedema and sometimes erythema occur at varying points in the 

 body, and occasionally the lymphatic glands become swollen. 



The classical land of the tsetse disease is in the neighbourhood of the 

 Zambesi. There it was seen and very well described by Livingstone ; 

 but, unfortunately, further investigations have shown that tsetse disease 

 extends over the whole of Africa. 



Whilst the trypanosomata of rats can only be conveyed to the one 

 species, those of tsetse disease thrive in all mammals, particularly in the 

 horse, mule, ox, dog, rat, and mouse. 



The tsetse organism has been shown to kill both horses and mules, 

 but to be less dangerous for oxen. A certain relative immunity exists in 

 some races. As regards the ass, observers are not agreed ; Koch failed 

 to infect it. Sheep and goats are also but slightly susceptible. The 

 conveyance of trypanosomata from the blood to uninfected animals 

 occurs through the medium of a stinging fly (the Glossina morsitans) . 



Surra is endemic in the Philippines, Java, and the island of Mauritius. 

 Koch regards the trypanosomata of surra as strictly analogous with the 

 parasites of tsetse disease. Horses (and, in India, elephants) especially 

 sufi'er from surra. Although the Glossina morsitans does not occur in 

 India, other stinging flies replace it and convey the disease. 



Another variety of trypanosomiasis is mal de caderas, seen in 

 South America, particularly in Argentina and Brazil. It aft'ects horses. 

 According to Koch, the parasites of mal de caderas exactly resemble 

 the tsetse and surra parasites. Other observers, however, declare that 

 the mal de caderas parasites are distinguished from those before men- 

 tioned by their particularly small centrosome. Mal de caderas affects 

 not only horses, but all the other animals which suffer from tsetse. 



