Ranson, spinal Nerves. 105 



may be designated as old. It would seem, however, that the 

 point concerning their incapacity for further development is not 

 so well taken. We will return to these points in another para- 

 graph, and will now consider Buhler's conception of the raisori 

 d'etre of the small cells. 



BiJHLER ('98) noticed that under physiological conditions in 

 the toad, the frog and the rabbit there occurred a degeneration 

 of a few isolated large ganglion cells, which were however not 

 described. The degeneration is, to all appearances, not very 

 rapid; in a spinal ganglion of a frog about 20 or 25 at a time, in 

 rabbits relatively much fewer. He assumes that these disappear- 

 ing ganglion cells are recruited from the ranks of the small cells, 

 which develop into large cells as they are needed. "Since after 

 the earliest stages a proliferation of ganglion cells no longer occurs, 

 in order to remain capable of functioning throughout the period 

 of life, the spinal ganglion must receive for its portion in the anlage 

 sufficient reserve material in the form of undeveloped cells." 

 Hatai ('02) has argued against this assumption on the ground 

 that the number of spinal ganglion cells is approximately constant 

 throughout the life of the individual. However the recent obser- 

 vations of KosTERon the spinal ganglia of cats, dogs and rabbits 

 give some support to Buhler's statement (Koster '03, p. 1098). 

 "One recognizes, in every section of a normal ganglion, cells with 

 all possible appearances of degeneration. One can see cells with 

 eccentric swollen or fragmented nuclei, coarse and fine chromato- 

 lysis, and all the changes which one may look upon as the reac- 

 tional manifestations of the cells to the physiological degeneration 

 found by Sigmund Mayer in the peripheral nerves. We can, 

 therefore, speak of a physiological degeneration of nerve cells." 

 From these observations it would seem not impossible that a cer- 

 tain very slight amount of degeneration is going on constantly 

 in the normal ganglion; and the question, whether or no the small 

 cells are, as Buhler assumes, capable of replacing the cells lost 

 in this way, is a question worthy of some consideration. 



Hatai ('00) has given some attention to the significance of the 

 small darkly staining elements, which with their scanty cyto- 

 plasm and large nuclei present many of the characters of embry- 

 onic cells, and concludes that they are "in a growing state or in a 

 more or less permanently immature condition." In order to 

 test this assumption he ('02) counted the number of large and 



