548 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



and seems likewise sustained by our analysis, so far. Indeed, 

 we have seen that the axis-cylinder, if our interpretation is 

 sound, is able, through the presence of its coat of myelin and 

 its plasma-containing fibrils, not only to supply chemical' 

 probably nervous energy, but also to undergo nutritional 

 metabolism. Can we say the same of the cell-body of the 



neuron: 



We have seen that the fibrils penetrate the nerve-cell, and 

 that various poisons, as shown by Lugaro and Levi, cause them 

 to become "very distinct." Referring to the intracellular 

 distribution of the fibrils, Barker says of Apathy: "He de- 

 scribes the finer peripheral neuro-fibrils as follows: They are 

 seen to enter the cell-body and passing out to the peripheral 

 part of its protoplasm, there to break up into a complicated 

 plexus composed of anastomosing elementary fibrils in the 

 outer chromatic zone. From this peripheral plexus there pass 

 through the 'inner alveolar' zone radial branches to the in- 

 ternal chromatic zone, in which is to be -seen another fine 

 plexus of elementary fibrils, which, anastomosing and converg- 

 ing, finally form the single strong motor neuro-fibril, which 

 passes out of the cell through the very center of its pyrifcrm 

 process. In other animals studied by Apathy there are cells 

 with definite dendrites entirely separate from the axon and in 

 these the cellulipetal neuro-fibrils enter ~by way of the dendrites, 

 ramify and anastomose freely inside the cell-body, and then, 

 reuniting, take their exit from the cell by way of the axon. Similar 

 relations exist in the ganglion-cells of the vertebrates which 

 he has studied thus far." 



This strikingly coincides with the course of the plasma- 

 fibrils or capillaries as we interpret it. Indeed, if the fibrils 

 enter the cell, form a plexus therein, and pass out "by the way 

 of the axon": fibril, plexus, and axon represent a continuous 

 channel which must contain plasma, since we have ascertained 

 that the axon contains this fluid. Again we obtain a clear 

 indication as regards the path of the blood-stream: it enters 

 by the dendrites and passes out by way of the axon. It is with 

 the dendrites, therefore, that the vascular neuroglia-fibers 

 found thickened, globular, etc., by Berkley in his poisoned 

 animals must be connected. But this fact suggests that these 



