100 Mr. Plimmer. Effects on Rats of the Trypanosomata [Nov. 21, 



which we know nothing, which produces not only changes in the morphology 

 of the organism, but also in its pathogenic effects, for, from the above 

 experiments, it can be seen that the inoculation of these short forms may, 

 in the first or subsequent passage, give rise to the long form in the inoculated 

 animal, with quite different symptoms (cf. figs. 3 and 4 : fig. 3 photographed 

 from a smear of spinal cord of Eat 66 b, and fig. 4 from a blood film of Eat 69, 

 which was inoculated from Eat 66 b). 



5. Pathological Anatomy. 



The examination of these two series of rats has shown that the pathological 

 effects are fairly uniform in each of the two types of cases. 



In those animals in which paralysis occurred, the principal lesions were 

 found in the spinal cord. There was invariably congestion of the vessels, and 

 in eight cases well marked haemorrhages around and in the substance of the 

 cord. There was the characteristic exudation around the blood-vessels of 

 mononuclear cells, and of plasma cells, such as Dr. Mott has described in the 

 brain in cases of Sleeping Sickness ; and in all the cases a varying amount of 

 glia proliferation (vide figs. 1 and 2). The nerve-cells in the affected areas of 

 the cord were degenerated in varying degrees up to the disappearance of the 

 processes, and even of the nucleus with vacuolation of the protoplasm. 



The brain showed much less change, and only in the chronic cases was 

 any exudation found around the vessels. Small haemorrhages in the 

 meninges were seen in five cases. 



Trypan osomata, mostly in stages of degeneration, Were found scattered 

 through the substance of the cord and brain in varying numbers ; none were 

 found in the vessels, which were generally distended with blood. 



The other organs showed very little change ; they were anaemic and firm ; 

 the spleen was not enlarged in the chronic cases with marked paralysis, and 

 was only slightly enlarged in the transitional cases. There was no enlarge- 

 ment of the superficial or deep lymphatic glands, and the eyes and genitals 

 were normal. 



In the cases in which the trypanosomata were plenteous in the blood, and 

 which had no paralytic symptoms (the Gambia Fever type), the brains and 

 cords were very congested, and the blood in the distended vessels contained 

 large numbers of trypanosomata. None were seen in the substance of the 

 brain or cord. In six cases small haemorrhages were found on the meninges. 

 There was no degeneration of the brains or cords. 



The superficial lymphatic glands were often enlarged. The abdominal 

 glands were always enlarged, and some of both superficial and deep glands 

 were reddish to brown in colour. The enlarged glands showed changes of a 



