1018 
2.  Table  showing  the  total  numbers  of  axons  in  the  dorsal  and  ventral  roots  of  animals  ol 
various  ages  in  the  same  species  and  of  different  species. 
Age  in 
Total  nurnber  of 
Relation 
Average 
Percentage 
Species. 
days  or 
length 
rootsofthespinal 
nerves. 
between  the  i 
numbers  in 
the  dorsal 
total. 
of  increase 
Remark 
in  cms. 
ventral 
roots. 
Dorsal 
roots. 
and  ventral 
roots. 
V.  r. 
D.  r. 
V.  r. 
D.  r. 
Mus  musc.  var. 
Days 
I 
i 
1 
albus.  5 
550 
23075 
48880 
2.11:1  ) 
23067 
48639 
1 
i 
,,  2 
550 
23060 
48399 
2.09:1  £ 
t 
M » 5 
189 
19588 
38122 
1.94  : 1 
„ V 2 
189 
18586 
37116 
1.99  : 1 
i 
» „ 5 
151 
16523 
35097 
2.12  : 1 
; 1 
,,  » 5 
77 
16215 
33888 
2.09  : 1 
80 
105 
n 1)  5 
49 
15414 
27279 
1.76  : 1 
' 
» >1  5 
25 
14236 
26136 
1.8  : 1 
! 
» )»  5 
' 10 
12825 
! 23874 
1 1.86:1 
II  $ 
i 10 
12762 
24190 
1.89:1  1 
II  II 
4 
12431 
23824 
: 1.9  : 1 f 
12814 
123715 
j 
II  II 
4 
12497 
23311 
i 1.86:1  ( 
II  II 
4 
12936 
23432 
1.81  : 1 1 
II  II 
4 
13432 
23663 
i 1.7  : 1 ' 
129 
Days 
about2190 
15970 
i 
1 31229 
1.92  : 1 
Average 
i 
i 
Canis  fam.  9 
183188 
393489 
2.14  : 1 
183188 
393489  . 
» „ 5 
1 „ 1277 
139808 
278879 
1.99:1 
1 
1 72.7 
73.9 
» „ 2 
1 " 
106072 
i 226264 
i 2.13:1 
106072 
1226264/ 
! 
„ „ 2 
17 
134867 
245089 
I 1.81  : 1 
1 
' 
» „ 2 
60 
124401 
' 237839 
1 1.91  : 1 
1 
1 
! 
i 
710 
137667 
! 276312 
i 2 
1 
1 
j 
by  the  above  table,  which  also  illustrates  to  some  extent  the  mag- 
nitude of  the  increase.  The  increase  in  the  nurnber  of  axons  is 
proportionately  greater  during  the  first  part  of  the  period  of  growth 
than  dnring  the  latter  part,  which  is  probably  not  completed  in  any 
of  (he  gronp  of  animals  included  in  the  table.  It  is  interesting  to 
