150 Journal of Agricultural Research voi. xvin. no. 3 



In sections from the lower lumbar and sacral region stained by Van 

 Gieson's method the deviations were more apparent than in the lumbar 

 region. 



The dorsal and ventral horns and the gray commissure appeared to 

 have an increased quantity of neuroglia fibers. The Rolandic substance 

 capping the dorsal horns was more distinct. The central canal in the 

 middle of the gray commissure was enlarged. The single row of ependyma 

 cells lining the canal were somewhat flattened, probably by pressure of 

 spinal fluid, which distended the central canal. The central gelatinous 

 substance, which is a modified neuroglia surrounding the central canal, 

 appeared to be increased in amount and to contain hypertrophied glia 

 cells. Simple dilatation of the central canal of the spinal cord is known 

 as hydromyelia. When the dilatation becomes very extensive it is 

 difficult to distinguish this condition from the hollowing out of the central 

 canal by a process of softening known as syringomyalia, which is however 

 usually found in the cervical region. . Neither the motor-nerve cells of 

 the ventral horns, the sensory-nerve cells within the dorsal horns, nor the 

 cells of the column of Clark showed marked abnormality when stained 

 by the Van Gieson method. There was, however, an increase of neu- 

 roglia tissue in the vicinity of the dorsal median groove, dorso-lateral 

 grooves, and the entrance and course of the dorsal nerve roots. This 

 increase of neuroglia was not sufficient to constitute sclerosis of the 

 dorsal column. Sections that were stained by the Nissel method showed 

 what may be regarded as the beginning of chromatolysis. The constitu- 

 ents that are most susceptible to influences are the Nissel bodies or 

 chromatophil granules. While the mechanism of chromatolysis is still 

 obscure, it is generally believed that the process represents the reaction 

 of the cells to the disturbing forces, resulting in disintegration of the 

 chromatophil granules in various parts of the cell, and is spoken of as 

 peripheral, perinuclear, and disseminated. 



Slight peripheral and perinuclear disintegration was observed in the 

 sensory-nerve cells and to a less degree in the motor-nerve cells and the 

 cells from the column of Clark. Neurologists generally consider that this 

 latter condition is reparable or that the functional activity of the nerve 

 cells is only partly impaired; but when the cell becomes deprived of its 

 functional activity a further step in chromatolysis is produced that is 

 not reparable, constituting a later stage of degeneration known as acro- 

 matolysis or plasmolysis. This latter condition was observed in sections 

 from the lumbar region. No other method was so sensitive as the Nissel 

 method in showing the earliest change of chromatolysis in the ganglian 

 cells. Sections stained with Pal's modification of Weigart's method 

 showed slight alterations. The bluish slate color of the medullated nerve 

 fibers of the white substance showed good contrast with the yellowish 

 stained gray substance which has only a limited number of medullated 



