

THE PHYSIOLOGY OP THE NEURON. 527 



cent and plumed collaterals, and he states that in these cells 

 two different phases can be observed: first, a stage of contrac- 

 tion, that is, a stage in which the cell-processes become short- 

 ened; and, secondly, a stage in which the cell is relaxed, that 

 is, a stage in which the processes of the neuroglia-cells are elon- 

 gated. He maintains that the processes of the neuroglia-cells 

 represent an insulating and non-conducting material, and that 

 during the stage of relaxation these processes penetrate between 

 the arborizations of the nerve-cells and their protoplasmic 

 processes, and so make difficult or impossible the passage of 

 the nerve-currents; on the other hand, in the stage of contrac- 

 tion the processes of the neuroglia-cells are retracted, and they 

 no longer separate the processes of the nerve-cells, and the 

 latter are thus permitted to come into contact. 28 Evidently 

 Ramon y Cajal admits the very thing against which he con- 

 tends, for if the nerve-cell processes are at one time not in 

 contact and at another are in contact, they must certainly 

 move, and the question before us is self-admitted. It matters 

 not whether the processes of the nerve-cells move little or 

 much, but that they move at all is the question at issue, and 

 this Ramon y Cajal admits, though he makes the movement 

 a purely passive one." 29 To us it appears clear that, since 

 Ramon y Cajal held the nerve-cell to be a passive structure, 

 requiring an independent connecting-link to close the circuit 

 with the adjoining cell, he must have denied both the gem- 

 mules and the varicosities any physiological importance. His 

 opinion, therefore, that normal material cannot be differen- 

 tiated from toxic material, when applied to the retraction of 

 gemmules and the formation of varicosities, cannot be said to 

 rest upon solid premises, and, for the time being at least, to 

 in no wise affect the question. 



In a comprehensive review of the anatomy and physiology 

 of the nervous system, L. F. Barker 30 makes the following re- 

 marks: "The physiologist of the present day sees in the func- 



28 We will see farther on that Cajal's observation as to the relaxation and 

 contraction of neuroglia-cell processes is valuable in that it proves that the tips 

 of the gemmules do not transmit nervous energy. S. 



^Dercum: University Medical Magazine, April, 1897. 



80 L. F. Barker: New York Medical Journal, May 15 et seq., 1897-98. 



