ETIOLOGY 



413 



a dog will usually produce the disease. Ibe parasite disap- 

 pears from the blood and tissues very rapidly after death, 

 so that to prove successful, inoculations should be made 

 from an infected individual before or immediately after death. 

 Thev are not affected after forty-eight hours. 



Schneider and Buffard, Nocard and others found the try- 

 panosoma in the blood and exudates of horses, asses and dogs 

 suffering from dourine. They failed to find it in the same 

 localities in animals of the same 

 species which were free from 

 dourine. The infected blood 

 preserved for 24 hours in sealed 

 glass tubes, and then inoculated 

 into dogs produced character- 

 istic symptoms and lesions with 

 many trypanosoma in the blood. 

 Inoculation into two other dogs, 

 with the same material, but at 

 the end of 48 hours, produced a 

 slight transient hyperemia only, 

 without local lesions or propaga- 

 tion of the parasite in the blood. • ^ ^^^ , ^ 

 The blood from the same animal inoculated after filteen days 



p-ave negative results. 



Baldrey found Romanowsky's and Wright's modifications 

 of Leishman's method the best methods for staining the try- 

 panosoma ; the latter is very useful and hand3^ as no mixing 

 of solutions is necessary and no fixing required. 



The following is Romanowskf s Stain : 



STOCK Sor.CTION NO. I. 



T,, -1 part 

 Hdchsfs Medicinal Methylene Blue ^ ^ ^^^^^ 



Sodium Carbonate pure ' ^^^ p^^^^ 



Distilled water 



Place this solution in an incubator at 37° C. for two or three da 

 when a purple color will be noticed at the edges of the liquid tins 

 depends u on the formation of a new red color-niethylene red-which 

 crbinedlitheosin forms the active principle of the stain and has a 



Fig. 109. Trypanosoma of dou- 

 rine in the process of division 

 {after Lignieres). 



