10 Dr. R W. Mott. Microscopic Changes in the [Feb. 21, 



destruction as in general paralysis of the insane. This functional depression 

 of the neural elements may be accounted for, by (a) increased intracranial 

 pressure brought about by the retardation of the lymph circulation and the 

 cell proliferation ; (b) the interference with the blood circulation, and with 

 the gaseous and metabolic exchanges between the blood and the lymph, and 

 between the lymph and the neurone ; (c) in chronic cases by a certain amount 

 of neurone destruction as shown by Marchi's degeneration of fibres, find a 

 certain amount of cell and fibre destruction. 



DESCRIPTION OF PLATES. 

 Plate 1. 



In these figures only the neuroglial tissue is shown. Magnification x 500. 

 Fig. 1. — Proliferating branching glia cells in the subpial tissues of the cortex in a case of 



very chronic uncomplicated human Sleeping Sickness. (Masake, ' Sleeping 



Sickness Reports,' vol. 6, p. 234.) 

 ,, 2. — Extension of i,he proliferated glial tissue along a septum of the spinal cord, 



showing the processes of the glial cells extending on to a small collapsed vessel 



(Masake, ' Sleeping Sickness Reports,' vol. 6, p. 234.) 

 „ 3. — Various stages in acute glial cell proliferation, seen abundantly in the brain 



tissues of the monkey, dying eight months after infection by fresh fly feeding. 



Lymphocytes (I) are also seen. 

 „ 4. — Ditto with branching glial cells, their processes enveloping and extending on to a 



wall of a small vessel. 



„ 5. — Yery marked glial proliferation around a small vessel. The cells are older, being 

 much larger and their processes more numerous and extensive. A long process 

 can be seen extending from the large branching neuroglial cell and termina- 

 ting in a foot on the wall of the vessel. This represents the glial proliferation 

 found in a monkey which died with lesions similar to human Sleeping Sickness. 

 These drawings were made from preparations of 10 /x thickness, stained by 

 polychrome and eosin method. The body and processes of the neuroglial 

 cell stain pink, the nucleus purple. 



„ 6. — Section of degenerated root of 30th segment of the spinal cord dourine, stained 

 by Van Gieson's method. 



All the nerve-fibres have disappeared. Preparations stained by "Weigert 

 method show that nearly all the fatty matter has been absorbed ; the axis 

 cylinders have disappeared and no regeneration has occurred. The endoneurion 

 is highly vascular, proliferated, and increased in amount. The circular spaces 

 corresponding to the degenerated nerves are still seen, but no nerve-structure 

 is left. The clear space seen in the centre of the enlarged neurilemmal cell 

 corresponds to the space formerly occupied by the axis cylinder and its coating 

 of myelin. From its colour and high refraction, it is probably filled with fat. 



Plate 2. 



Fig. 1. — Drawing of the inflammatory exudation around 30th segment of the lumbo-sacral 

 spinal cord, with attached membranes and roots, Dourine. Stained by Van 

 Gieson's method. Magnification X230. 



