56 REPORT ON DOURINE. 



trypanosoma or its developmental form lies in a dormant state in 

 the tissues bnt ready to spring into activity at short notice, as 

 evidenced by the fact that when the inoculated animal is subjected 

 to lowering or depressing conditions, further and more advanced 

 symptoms of the malady quickly become apparent. When the try- 

 panosoma has obtained an entrance into the general circulation, the 

 eruption of cutaneous plaques may occur at any time after an in- 

 terval of a few days, and may recur at intervals for long periods 

 exceeding a year. The exhibition of further symptoms during the 

 course of the disease, be they nervous, articular, or cutaneous, are 

 all due to the presence of the trypanosoma, which has made its 

 entrance into the tissues of each particular part of the body 

 affected, and there brought about inflammatory and other 

 changes. 



III. Where does the trypanosoma rest in stallions during 

 the prolonged latent period characterized by slight tumefaction of t>he 

 penile sheath ? Up to the present time it has not been accurately 

 determined (1) whether the trypanosoma becomes generalized 

 throughout the system, in stallions which present for long periods 

 the latent form of Dourine, (2) or the developmental form of the 

 trypanosoma remains dormant in the swollen penile sheath of 

 the affected animal until such time as depressing conditions reduce 

 its vitality. 



In one case the semen of such an inoculated animal after the 

 first covering did not appear to contain the trypanosoma or the 

 developmental forms, and the blood from the general circulation did 

 not reproduce the disease when inoculated into a susceptible animal. 

 In some cases it would appear possible for the trypanosoma or 

 rather the developmental forms of the same to be shut off for a 

 time in the affected part, identical changes taking place in the 

 localized swelling of the penile sheath to those occurring during 

 the persistence of a plaque which will be described subsequently. 

 In some cases it would appear as if the trypanosoma is more or 

 less cut off for a period in the lymphatic vessels, for these occasion- 

 ally may be seen enlarged and more or less varicosed. 



IV. What is a plaque ? The Dourine plaque is a form of 

 Urticaria or nettle-rash, the characteristic lesion of which is a raised 

 patch or wheal. Urticaria is an Angio-Neurosis, or affection of 



