180 



PHYSIOLOGY 



CHAP. 



true axis-cylinder process, e.g. those of the stratum granulosum of 

 the olfactory bulb. The cells of the spinal ganglia of Teleosteans and 

 the cells of the cochlear ganglion are bipolar or bineural, i.e. have 

 two axons (Fig. 115, A), and in the molecular layer of the cerebral 

 cortex, according to Eamon y Cajal, Eetzius, and others, there 

 are nerve -cells with two or three axons. Veratti, however, 

 contests this statement, and gives a totally different interpreta- 

 tion to the data on 

 which it is based. 

 According to Golgi 

 the cells of the cere- 

 bral cortex which give 

 origin to the so-called 

 pyramidal tracts, and 

 still more those of the 

 ventral horns of the 

 spinal cord, have long 

 axis-cylinder processes 

 which give off col- 

 lateral rami, while 

 they preserve their 

 individuality for a 

 long distance ; the 

 latter are continued 

 in the ventral root- 

 fibres of the spinal 

 nerves (Fig. 116). 

 The cells of the dorsal 

 horns of the cord, on 

 the contrary, and 

 many cells in the grey 

 matter of the large 

 cerebral centres, have 

 short axis - cylinders, 

 which repeatedly 

 divide and subdivide, 

 and soon lose their individuality (Fig. 117). It is, however, very 

 doubtful whether the presumably different functions of these 

 various forms of neurones are connected with the morphological 

 differences indicated by the appearance of their axis-cylinders. 



The neurone theory, which regards the elementary components 

 of the nervous system as morphologically distinct, is not based 

 on any conclusive evidence. Even after the observations of 

 Eamon y Cajal and his numerous adherents* Golgi and his pupils 

 still insisted on the theory of a diffuse: nervous network, formed 

 of the collateral rami given oft' from the axons in the vicinity 

 of the ganglion cells. Golgi demonstrated this diffuse nervous 



FIG. 117. Large cells with short axons. Golgi's second type, 

 found in the nuclear layer of the cat's cerebellum, high 

 magnification. (Golgi.) In order to distinguish the proto- 

 plasmic processes from the nerve processes or axis-cylinders, 

 the former are printed in black, the latter with their rami- 

 fications in red. 



