tJiat spread Disease. 23 



nagana or tsetse-fly disease. In the horse the onset of an attack 

 may be detected by the coat staring, and by a watery discharge 

 from the eyes and nose. Shortly afterwards there appears a 

 general swelling of the belly and hind extremities, which fluctuates 

 from day to day. The animal hangs its head, and there is a 

 general emaciation, sometimes accompanied by blindness. Death 

 results from exhaustion ; there are no symptoms of pain, and the 

 appetite continues good till the last. In the dog the disease runs 

 a rapid course, and is invariably fatal. The chief symptoms are 

 extreme emaciation, swelling of the extremities, eruption over the 

 body with the formation of blebs and pustules containing more or 

 less purulent matter, and finally milky opacity of the cornea 

 giving rise to blindness. 



FIG. 5. ORGANISMS OF SLEEPING SICKNESS, 

 Trypanosoma gambiense, and red blood -corpusc les ; X 1,500. 



A map of Central and Southern Africa is exhibited, showing 

 our knowledge of the distribution of the tsetse-flies (Glossina) in 

 1911, at the time of the issue of Mr. E. E. Austen's " Handbook 

 of the Tsetse-Flies," published by the Trustees of the Museum. 



Around the lower part of the case are shown enlarged coloured 

 illustrations ( X 6) of the ten species of tsetse-flies that were 

 known at the time of the publication of the book in 1911. 



Displayed upon the glass shelf in the case are greatly enlarged 

 transparent models ( x 6,000) of red blood-corpuscles and a form 

 of trypanosome (T. Icwisi Kent) found commonly in the blood 

 of rats. Trypanosomes are small, elongated, parasitic animals 

 occurring in the fluid part (plasma) of the blood; they have an 

 undulating membrane or longitudinal fin which runs along the 



