284 AllSENIC AS ITvOPHYLACTIC. 



On Exp. 251 (the non-fatal case), in which the donkey, 

 having been placed on 12 grains of arsenic on February 13th, 

 after htematozoa had been discovered in its blood three days 

 earlier, was still alive on J uly 1 9th, in spite of several visits to 

 the " Fly Country " in the interval, the author's " Remarks " 

 are as follows : — 



" The preceding chart gives the principal facts of what is up 

 to the present the most successful case I have had of treatment 

 by arsenic. After five days of treatment the hteniatozoa are 

 seen to disappear from the blood and not to return for a period 

 of almost five months. The red blood corpuscles, which in 

 February lie between three and four millions per cubic milli- 



Fig. 16. 



Donkey suffering from Tsetse-fly disease, or Nagana 

 (after Bruce). 



metre, are seen to gradually rise in numbers to five millions. 

 Corresponding with this there has been a gradual increase in 

 fitness, and at present the donkey has all the appearance of a 

 perfectly healthy animal. The arsenic was stopped on the 

 17th May, but the ha^matozoa reappeared on July 10th, when 

 the animal was again placed on arsenic " (p. 64). 



" B. — Arsenic as a Prophylactic Agent " (pp. 64-66). 



The author commences this section with the following para- 

 graph : — 



" As has been seen in the cases in which arsenic was given as 

 a curative agent, the drug undoubtedly markedly modified the 

 course of the disease. It, therefore, seemed probable that the 

 disease would be prevented altogether if the arsenic were given 

 for some time previous to the animal being exposed to the 

 infection. If twelve grains of arsenic given daily can cause the 

 hjematozoa to disappear rapidly out of the blood, it is difficult 

 to imagine how they could appear in the first place if the animal 

 before entering the Fly Country had been given this quantity of 

 the drug for some time previously. But twelve grains daily is a 



