58 'Journal of Comparative Neurology and Psychology. 



The formation of vacuoles has long been recognized as one of the necessary 

 imperfections in most methods of fixing of nerve cells. The writer cannot agree 

 with the statement often seen that the vacuolation may be regarded as pathological 

 only when it is found in advanced degree. Among the present cases, extreme 

 vacuolation when found, was always plainly referable to post-mortem processes. 

 The study of cadaveric changes in ganglion cells indicates that vacuoles are one of 

 the most constant of post-mortem products; and that they frequently form in con- 

 siderable numbers and of large size within a few hours, often preceding other post- 

 mortem changes. Especially when the brain and meninges are cedematus, or 

 when the patient has suffered from general sepsis, vacuolation of cells may be 

 expected unless the tissues are fixed very shortly (one half hour) after death. The 

 above observations, as well as the circumstances under which vacuoles are usually 

 found in stained specimens, indicate that in the great majority of instances vacuola- 





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Fig. 7. Fig. 8. 



Fig. 7. Arion rufus. Vacuolated condition of cytoplasm and granules in the axone hillock. After 

 Legendre ('05, Fig. i). 



Fig. 8. Ganglion cell of Tethys with a number of mitochondrien masses either in clear spaces limited 

 by a definite wall or free in the cytoplasm. After Rhode ('04a, Fig. 10). 



tion of ganglion cells is a cadaveric or artificial product, and in any case with the 

 present state of our knowledge, is devoid of definite pathological significance. It 

 is doubtful if the structures known as nucleolar vacuoles are to be regarded as of 

 a similar character with the vacuoles of the cytoplasm. 



Rhode presents numerous facts in his several papers in regard to the structure 

 of the ganglion cell. The sphere referred to in the following is a differentiation 

 of the cytoplasm of a distinct character and should not be confused with the sphere 

 associated with the centrosome. According to Rhode ('04a) the sphere in the 

 ganglion cell of Tethys consists of a central part surrounded by a clear layer having 

 the granules arranged compactly and in a radial manner. The clear layer is made 

 up of a homogenous or fine granular substance which colors intensely (Fig. 8). 

 The outermost bodies in the peripheral layer of granules may fuse completely so 



