It I PORT ON DOURINB. 81 



plaque appeared during the night of the 2nd and 3rd of April, on 

 the 232nd day after the appearance of the primary symptom and 

 within 72 hours of being detrained. 



It would appear that, owing to the reduction in energy brought 

 about by one of the abovementioned causes, a loss oi power of 

 resistance was produced in the respective animals, which allowed of 

 the trypanosomata developing and thriving in blood which pre- 

 viously had been an unsuitable medium, and had held them in 

 cheek. 



Section IV SYMPTOMS. 



The course of this disease may on the one band be comparatively 

 rapid or on the other slow; the symptoms may vary in different 

 animals and breeds of animals so that an important symptom may 

 occasionally be absent; nevertheless in a great majority of cases one 

 is able to recognize in the development of symptoms several periods. 

 It must be observed that in dividing the course of this disease into 

 periods the appearance of the most important symptoms does not 

 always follow in definite sequence, and that one series of symptoms 

 may not have run its course and subsided before the succeeding 

 series make their appearance. What really is observed in practice 

 is an overlapping or a partially concurrent exhibition of certain 

 symptoms referable to the respective periods. However, in one 

 case the second train of symptoms had developed before the 

 appearance of the first was observed. For this reason the following 

 arrangement is purely an arbitrary one, simply utilized for the sake 

 of description. 



The characteristic phenomena exhibited in the course of 

 Dourine are referable to the genital organs, the skin, and to the 

 nervous system, and may be divided into three periods : 



(i) Characterized by changes to the genital organs and struc- 

 tures in close apposition. 



(ii) Cutaneous lesions of vaso-ueurotic origin. 



(iii) Lesions of the central nervous system. 



I. The symptoms during the first phase differ in the stallion 

 and the mare, and therefore will be described separately. 



