264 FISH. [Vol. X. 



intermediate cells always send their processes toward the 

 periphery ; the fusiform cells send their main processes 

 between the layer of cells and the alba, but their ends and 

 their branches point toward the periphery. If the lines of 

 least resistance were always followed by these processes it 

 would seem as if they would, in the case of these more ectal 

 cells, grow toward the cavity through the loosely arranged 

 cells rather than through the dense interlacing of the fibers 

 that comprise the alba. A plausible explanation for this fact 

 seems to be that of polarization ; that there is an inherent 

 power in the cell itself controlling the direction of the growth 

 of its process. 



In the unipolar type of cell found in DcsmognatJms it may 

 seem of doubtful propriety to differentiate one of the branches 

 of this single process as a neurite, simply because it is longer 

 than the others. The dendrites are in reality nothing more 

 than prolongations of the cell body, and in the cortex of some 

 higher forms the neurites are said to arise from them. Where 

 these two appurtenances of the cell are well developed, it is 

 quite probable that the dendrites subserve the important func- 

 tion of collecting the nerve impulse in transit, by means of 

 induction through propinquity and the neurite of discharging 

 it ; in other words, the dendrites are cellipetal in function and 

 the neurites cellifugal. 



Does the single process arising from the intermediate cell in 

 the Desmognathus represent a neurite breaking up into branches, 

 — a somewhat advanced neuroblast, or does the process com- 

 bine both neurite and dendrite, forming a neurodendrite t In 

 the unipolar cells of the spinal ganglia of higher forms a por- 

 tion of this single process is evidently cellipetal and another 

 portion cellifugal, the nerve impulse passing from the periph- 

 eral fiber to the nerve cell and back through the common 

 process of the cell to the central fiber. The evidences of 

 fatigue shown by the cell after electrical stimulation of the 

 peripheral fiber, in the experiments of Hodge, seem to confirm 

 this view of the matter. 



The unipolar cells in the central nervous system of Desmog- 

 nathus are not strictly comparable to the unipolar cells of the 



