951 



2. Table showing the total numbers of axons in the dorsal and ventral roots of animals of 

 various ages in the same species and of different species. 



i Ao-o in Total number of 

 \^^^ '" ! axons in all the 

 ' days or roots of the spinal 



Species. , ,. nerves. 



length 



in cms. ventral Dorsal 

 I roots. roots. 



Relation 

 between the 

 numbers in 



the dorsal 



and ventral 



roots. 



Average 

 total. 



V. r. 



D. r. 



Percentage 

 of increase 



V. r. I D. r. 



Remarks. 



Mus muse. var. 



albus. 



Days 

 550 



550 



189 



189 



151 



77 



49 



25 



10 



10 



4 



4 



4 



4 



129 

 Days 

 Cam's f am. $ about 21 90 



1277 



6 



17 



60 



710 



23075 

 23060 

 19588 

 18586 

 16523 

 16215 

 15414 

 14236 

 12825 

 12762 

 12431 

 12497 

 12936 

 13432 



48880 

 48399 

 38122 

 37116 

 35097 

 33888 

 27279 

 26136 

 23874 

 24190 

 23824 

 23311 

 23432 

 23663 



15970 I 31229 



183188 393489 



139808 j 278879 



106072 ' 226264 



134867 245089 



124401 237839 



137667 ! 276312 



2.11 



2.09 



1.94 



1.99 



2.12 



2.09 



1.76 



1.8 



1.86 



1.89 



1.9 



1.86 



1.81 



1.7 



1.92 

 2.14 

 1.99 

 2.13 

 1.81 

 1.91 



23067' 



48639 



12814 



23715 



80 



"^— Average 

 183188 393489 



106072 226264 



72.7 



105 



73.9 



bv tlie above table, which also illustrates to some extent the mag- 

 nitude of the increase. The increase in the number of axons is 

 proportionately greater during the first part of the period of growth 

 than during the latter part, which is probably not completed in any 

 of the group of animals included in the table. It is interesting to 



