g20 Dourine. 



tliat in some cases paralysis develops in the region of some 

 of the peripheral nerves (Facialis!) eyen in the early stage of 

 the disease, and further that in the affected tissues the round 

 cell infiltration is always observed in the immediate vicmity 

 of small blood vessels. 



The intermediate attacks of fever appear to be produced 

 by periodical invasions of large masses of trypanosomes into 

 the blood stream, or by their temporarily rapid multiplication 

 in the blood. Their disappearance appears to be the result 

 of the development of trypanolytic substances. The trypano- 

 somes apparently exert their pathogenic action by the produc- 

 tion of certain toxins, which have not yet been demonstrated; 

 these on the one hand produce a serous inflammation of the 

 walls of the vessels, on the other hand they principally attack 

 the substance of the peripheral nerves, and the intervertebral 

 ganglia. In these a cellular infiltration of the nerve tissue 

 develops (neuritis interstitialis), whereupon the nerve fibres, 

 as well as the nerve cells, degenerate and finally disappear 

 entirely. The sensitive nerve bundles become involved in great 

 numbers, and in a more severe form than the motor fibres, 

 the affection of which results in a degeneration of the cor- 

 responding muscle fibres. The disturbances observed in the 

 movements and in the sensibility of the living animals are 

 the direct result of the inflammation and degeneration of the 

 peripheral nerves, while the emaciation indicates the action of 

 a toxin circulating in the blood. 



In cases in which the parasites disappear entirely from 

 the body a complete recovery may result even in cases in which 

 conspicuous nervous symptoms have already appeared, and 

 such instances are not rare in northern regions. As long as 

 the motor cells of the medulla and the spinal cord are intact, 

 new nerve fibres may form from the nerve cells or from the 

 stumps of their prolongations of the axis cylinder. This is 

 proved by the microscopical examination of cases in which the 

 disease process showed improvement, when the nerves will be 

 found to show fine pale stained, new nerve filaments (Marek). 



The dourine trypanosomes have a pronounced predilection 

 for the mucous membrane of the genitals, for they may be 

 demonstrated in these even after subcutaneous, intravenous or 

 conjunctival infections. They are evidently capable of passing 

 out of the blood vessels, producing exudation of blood plasma 

 and a cellular infiltration on the irritated place, and thus 

 cause among other symptoms an urticaria-like eruption of the 

 skin, the so-called dollar spots. 



Anatomical Changes. Carcasses of animals dead from 

 dourine are extremely emaciated, and show on the prominent 

 parts of the body sores resulting from continuous lying down. 

 The subcutaneous connective tissue is poor in fat, and in places 

 shows gelatinous infiltration. 



In stallions the connective tissue of the scrotum is in many 



