540 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



quoted: "If we assume, with Golgi and B. Haller, the existence 

 of nerve net-works, the conception is somewhat modified, but 

 we can still retain the nerve-units . . ." all of which 

 tends to show that, while the neuron doctrine stands on a solid 

 foundation, there is a stumbling-block in its way which has not 

 as yet been removed. Especially is this true since the investi- 

 gations of Apathy, of Naples, who, after several years' study, 

 has unquestionably demonstrated the existence of a net-work 

 of what he terms "neuro-fibrils." 



That Apathy's "neuro-fibrils" as well as Golgi and Haller's 

 nerve net-works are not nerve-elements, but fine capillaries 

 which serve for the circulation of blood-plasma, seems to us 

 probable. In the following extracts the italicized words will 

 serve to call attention to the various links between these struct- 

 ures and others that we have analyzed. Professor Barker sum- 

 marizes Apathy's views as follows: "Apathy has been convinced 

 for some twelve years that the nervous system is composed of 

 two varieties of cellular elements entirely different from each 

 other: nerve-cells and ganglion-cells. The nerve-cells, the 

 architecture of which is quite in accord with that of muscle- 

 cells, give rise, he thinks, to neuro-fibrils. A neuro-fibril, in 

 turn, passes out of a process of a nerve-cell and then goes through 

 a number of ganglion-cells, and ultimately, after leaving the last 

 ganglion-cell with which it is connected, passes more or less 

 directly to a muscular fiber or to a sensory cell. The neuro- 

 fibrils are, as conducting substance for the nerve-cells, what the 

 muscle-fibrillce are as contractile substance for the muscle. The 

 pathways to be followed by the neuro-fibrils are predestined 

 from the earliest embryonic stages, for they correspond, ac- 

 cording to Apathy, to the intercellular protoplasmic bridges" 

 That we have all required elements in support of our belief ia 

 evident; we have seen that muscle-fibers are, in reality, deli- 

 cate tubes; that vascular channels for the transmission of 

 blood-plasma should be protoplasmic is as obvious as is the 

 need of their penetrating into and out of the cells. 



What appears to us as conclusive evidence is indirectly 

 afforded by the deductions of Ehrlich, suggested by his study 

 of the methods of staining living nerve-cells and their processes 

 with methylene-blue. "Ehrlich found," says Barker, "that by 



