Doiirine 75 



covered in recently formed plaques. Baldre}' says, in reference to 

 the appearance of the trypanosoma in the fresh plaques, ' ' If these 

 appear, then a positive diagnosis can be made ; if not, the case 

 is not Dourine." The parasites are said to disappear quickly 

 from these plaques, so that it is dificult or impossible to find them 

 after twenty-four hours. They may be found in the discharges 

 from tie vagina or urethra of the infected animal, but it seems 

 that their existence here is not so uniform as in the fresh plaques. 

 Some investigators believe that they are quite uniformly present 

 in the spinal fluid. It is frequently very diflficult to discover 

 them in the blood. 



This parasite constitutes an exception to the general rule in 

 the trypanosomic group of diseases, in that it is not transmitted 

 from animal to animal by the bite of an insect. For laboratory 

 uses it is generally cultivated in dogs. 



Symptoms. The period of incubation following natural in- 

 fection is not definitely determined and varies considerably in 

 different cases. Generally there appear some physical signs of 

 disease in from eight to ten days after exposure, but these may 

 not be very marked and may pass unnoticed by an inexperienced 

 obserA^er. 



The symptoms of the disease may be divided into three im- 

 portant groups ; the local lesions of the genital organs and the 

 contiguous parts ; those of the .skin and other mucous mem- 

 branes than that of the genital organs ; and the symptoms which 

 emanate from the central nervous system. 



The local symptoms in the genital organs are the first to 

 appear after infection and usually the last to disappear in case of 

 recovery. 



In the stallion there usually appears after eight or ten days, 

 subsequent to infection, a swelling of the penis and prepuce, with 

 some degree of protrusion of the penis from the sheath, still 

 covered by the prepuce. The prepuce shows a tense, elastic 

 swelling and has a smooth, glistening appearance. If the uretha 

 is exposed to view, its meatus will be found swollen, dark red 

 and intensely injected. From it exudes a small amount of a 

 thin, dirt}^, muco-purulent discharge. As the disease progresses, 

 the tumefaction of the prepuce and penis increases and extends 

 to the sheath and scrotum, which may eventually become enorm- 

 ously swollen and remain in an indurated condition for one to 



