956 



other hand, a'^ b; then one ought to succeed in finding figures 

 of division of the nerve fibres in ab; if, finallj, a<^b, then, of 

 course, one ought to be successful in finding figures of growth in rtè. 

 For the ventral root the corresponding line of argument is, of course, 

 as follows: if r/j = èj, then there are probably neither figures of 

 division nor growth in the piece n^b^-, if rf, ]> ój, there are probably 

 figures of growth in a^b^; if a^ <^ /^,, there are probably figures of 

 division in ci,6,. 



In not a single case did the calculations that were carried out 

 give values for a that weie greater than those of b, nor values for 

 61 greater than those of a^. The two values for each root in older 

 animals were — apart from the possibility of error (about 

 2 7o) — equally large. In young animals, on the other hand, as a 

 rule <f <^ b and (i-^'^b^. As examples we may give the values for 

 S. 1 (left side) in a pup|)y sixty days (»ld : rz =r 9209, />= J1487; 

 a, = 3335, b, = 2623. 



If we correct these numbers according to the percentage of error 

 in the calculation, we then obtain: r/ = 9209 -f- 2 7, = 9393, 

 6 = 11487 — 2 V, =11251 ; ^, = 3335 -2V, = 3268, 6, = 2623 + 

 -f- 2 Vo = 2675. 



These figures are very clear evidence against the occurrence of 

 any figures of division in the pieces ab and aj)^ respectively in the 

 animals in question. On the other hand they indicate, of course, the 

 existence of a not inconsiderable number of figures of new growth 

 of axons. As far as I can see, 1 have found a small number of 

 certain figures of new growth — there are undoubtedly more of 

 these. These formations vary, of course, very greatly in their form. 

 Such great differences in the number of nerve fibres in a and b and 

 «J and b^ are, however, not always found even in young animals; 

 the differences are, as a rule, considerably less. 



I could not discover any possible method of verifying more effect- 

 ively the above-mentioned absence of any T- and ^'-division in the 

 spinal cord and the spinal ganglia of the nerve fibres that pass into 

 the roots, and have consequently to be content with the fact that 

 in the above-mentioned preparation no figures of division could be 

 detected in these parts. It might perhaps be said that the number 

 of cells in the ventral horns and in the spinal ganglia compared 

 with the number of axons in the ventral and dorsal roots respectively 

 might afford a means of verification. This is not the case, however, 

 as the number of the ganglion-cells in both the ventral horn and in 

 the spinal ganglion is always considerably greater than the number 

 of axons. (This is discussed in greater detail below.) 



