1906.] Nervous System in a Case of Chronic Dourine, etc. 9 



human Sleeping Sickness, there is in the spinal cord a universal proliferation 

 of the glia tissue extending along the subpial septa and vessels, without 

 apparently destroying the nerve fibres. (Vide Photomicrograph 9.) 



It is possible, therefore, that the lymphocyte accumulation in the peri- 

 vascular lymphatics does not occur until the neuroglia proliferation has become 

 advanced, and this may account for the fact that leptomeningeal perivascular 

 infiltration with lymphocytes (so-called chronic meningo -encephalitis) is not 

 met with in the nervous tissues of animals inoculated with various trypano- 

 somes, that die within a comparatively short time, either from exhaustion, or 

 from the poisonous effects of the infection upon the cells of the nervous 

 system or from secondary microbial invasion. 



Greig* concludes from his experiments that the onset of the symptoms of 

 Sleeping Sickness synchronise with the entrance of the trypanosomes into 

 the lymph spaces of the nervous system, and this is accompanied by an increase 

 of lymphocytes in the cerebrospinal fluid. Whether it be as Greig's experi- 

 ments suggest, that the continuous presence of the trypanosomes in the cerebro- 

 spinal fluid acts as a direct cause of irritation of the lymphatic structures of 

 the central nervous system ; or whether it be the result of the absorption of 

 toxic products from the multiplication of the trypanosomes in the lymphatic 

 glands ; or whether it be the extension of a chronic inflammatory process 

 from the paravertebral glands along the lymphatics of the vessels and nerves 

 proceeding to the cerebro-spinal axis, as seems probable in Dourine, one fact 

 is certain, and that is, the symptoms of Sleeping Sickness are associated with, 

 and the depth of the lethargy and chronicity of the disease is in great measure 

 proportional to, the extent and degree of leptomeningeal, septal, and perivascular 

 lymphatic cell proliferation. This cell proliferation is made up partly by an 

 overgrowth both in number and size of the neuroglial cells to form a dense 

 meshwork and partly of accumulated entangled and occasionally altered 

 lymphocytes. In proportion to this chronic lymphatic inflammation the neural 

 elements display relatively slight degenerative changes in cases uncomplicated 

 by microbial infection ; thus differing from Dourine, where there was very 

 obvious degeneration of posterior spinal ganglion cells and roots with corre- 

 sponding degeneration in the posterior column. 



The mind of a patient suffering with Sleeping Sickness remains clear usually 

 until near the end. He can easily be aroused from his lethargy, and compre- 

 hends what is said to him, replying in a slow, sleepy manner, and with 

 manifest disinclination to continue a conversation, or to exercise any mental 

 or bodily effort. These symptoms point to a functional depression of the 

 anatomical basis of the seat of consciousness rather than to a widespread 

 * ' Reports of the Sleeping Sickness Commission,' Vol. 6. 



