RHPORT ON DOURINE. 65 



that animal's blood into susceptible animals is then of a positive 

 character, for at such times the mature trypauosomata or the 

 developmental forms are always present iu the blood. During the 

 period of eruption of numerous plaques, a small dose of blood will 

 reproduce the disease, whereas during a long intermission a dose 

 100 times as large may be required to bring about a positive result 

 or even the latter amount may prove unsuccessful, for trypanosomata 

 or their developmental forms are generally present in number 

 under the first-mentioned condition, while in the second case they 

 are very sparsely scattered or entirely absent from the blood. 



The number of cutaneous plaques which appear in Dourine 

 animals varies considerably, and may be divided into three classes : 



(a) those in which the cutaneous manifestations are well marked ; 



(b) those in which they are badly marked ; and (<) those cases in 

 which they are absent. 



(a) As an illustration of the first class of cases, I mil give 

 that of an Arab stallion. This animal contracted the disease from 

 an Australian mare and exhibited 85 plaques during a period extend- 

 ing over 5578 days. 



(b) An Australian mare contracted the disease from an Arab 

 stallion suffering from the latent form of Dourine. This animal 

 developed four plaques 2 on the 116th day, one on the 150th, and 

 one on the 2&4th day after coitus. 



(c) A New Zealand animal, covered by the same stallion, 

 succumbed in 75 days to paralysip v/iihout developing auy plaques. 



From my observations it would appear that the Arab horse is 

 likely to contract a severe from of disease from the Australian 

 breed, whereas the Australian variety as a rule develops a mild 

 form of it from the Arab. But in the case of the mare which 

 succumbed in 75 days, it would seem probable that the trypano- 

 soma entered the system not by an abrasion in the vaginal in. m. 

 during coitus, but by the Fallopian tubes, for subsequent to the act 

 of covering, the os uteri was found to be fully dilated and the 

 sperm had been ejaculated directly into the cavity of the uterus, so 

 that a direct peritoneal infection may have resulted. 



XII. When and why does a plaque disappear? As lorn; as 

 the trypanosomata continue to increase in number in a patch, the 



f 



