1026 



That such degenei-tation is rather common is also proved by the 

 fact that no slight number of cells in a spinal ganglion of even a 

 young animal show signs of degeneration. The new growth in this 

 region has thus the task not only of replacing the ganglion-cells 

 that have been destroyed by degeneration, but also of increasing 

 their number. A fairly considerable inci'ease of this kind takes places, 

 as is shown above, during the animal's period of growth. To judge 

 from my preparations, nature seems in this generation to make use 

 of both mitotic and amitotic division. In no case have I been able 

 to refer the cells that show the latter type of division to such small 

 forms as those in which mitoses occur; the former cells seem to 

 belong to remaining ganglion c.ells that are somewhat older and 

 sometimes, at least, with a certain degree of development, for I 

 have been unable to find fully developed processes among them. 



Amitoses. 



Besides the figures of mitoses one also sees in the preparations 

 in question figures of cells which produce a strong impression of 

 being engaged in direct division. As shown below one sees cells 

 that seem to be in different stages of this division. The cells of this 

 type, however, always belong to the young ones, to those cells (in 

 the silver-impi-eguated preparations) that have taken a very slight 

 amount of silver or even none at all during the impregnation. 



The different stages of a direct division which are found in my pre- 

 parations appear as follows: One sees cells, in which the nucleolus 

 is being divided or has just divided (fig. \a and fig. 2b) and where 

 the two nucleoli are still in each other's immediate neighbourhood. 

 The two nucleoli then move away from each other and the nucleus 

 begins to show signs of incision in the middle (see fig. 36 and fig 26). 

 After this there follows a complete division. of the nucleus, which 

 is also frequently accompanied by a division of the protoplasmic 

 body, fig. 3a and fig. 2a. Fig. 3a must be interpreted as a young apolar 

 ganglion cell in which, after the nucleus had first divided into two, the 

 protoplasmic body began to divide in the middle, after which the two 

 nuclei again began a new division. The preparations in which these 

 observations wore made were particularly well fixed and impreg- 

 nated, so that it is fairly certain that there was no possibility of artificial 

 products. Another thing that further supports the idea of natural 

 formations is the fact that these figures above-mentioned do not 

 occur in such very great numbers. It is true that there are many 

 nuclei of ganglion cells (among the smaller ones) which have two 



