iv GENERAL PHYSIOLOGY OF NEEVOUS SYSTEM 183 



Whatever the value of these conflicting statements, and how- 

 ever certain it is that during their histogenetic development 

 the constituent elements of the nervous system are morphologi- 

 cally distinct and independent, it is far from proved that in 

 fully developed tissues the so-called " neurone " represents a 

 true morphological unit, and is not a fusion of many elements, 

 or syncytium ; nor that these neurones do not enter into close 

 relation by direct continuity of their protoplasmic substance ; 

 nor, lastly, is the idea of a diffuse fibrillary network which, both 

 in the central grey matter and at the periphery, knits the several 

 neurones into a single unitary system, comparable with the 

 vascular system, by any means excluded. 



This modern view of the minute structure of the nervous 

 system is founded on the work of Apathy,^ Bethe, Nissl, and 

 others, who, by new methods of staining, have brought out new 

 facts which are in more or less open contradiction with the 

 neurone theory. We must confine ourselves to a brief survey of 

 the principal data supplied by these researches. 



While the method used by Golgi and his numerous followers 

 in the study of the minute structure of the nervous system has 

 added greatly to our positive knowledge in this difficult subject, 

 it is by no means the best adapted to show up the microscopic 

 structure of the nerve-cells and processes. With too intense 

 impregnation with silver, both cells and processes are stJained 

 uniformly black. In order that this method may bring out the 

 fine structure of the body of the nerve -cell, as in the figures 

 obtained by Golgi, it is necessary to make repeated experiments, 

 for which no general rules can be given. 



Again, there is grave reason to suspect, on the strength of the 

 facts established by Apathy for the nervous system of the leech, 

 that the silver method which only shows up certain elements of the 

 system, leaving the rest unstained and therefore undifferentiated, is 

 inadequate for the demonstration of the finest ramifications of the 

 dendrites and axis-cylinders. We have seen that Golgi himself 

 pointed out that the free endings discovered by Eamon y Cajal, 

 upon which the whole neurone theory is based, are not indisput- 

 able, but result from an inherent defect in the method of staining. 



In 1871, in describing the ganglion cells of the spinal cord, 

 Max Schultze recognised the fibrillary nature of their protoplasm 

 and of the protoplasmic and nerve processes. Both in fresh 

 preparations and in those treated with osmic acid, he observed 

 distinct fibrils which run in various directions through the cell 

 body, giving it the appearance of a network or reticulum, and 

 are in direct connection with the elementary fibrils of which both 

 the axons and the dendrites are composed. He further assumed 

 the existence of a finely granular substance, which fills the 

 interfibrillary spaces. 



