1023 
otliei’  liand,  n^b;  Uien  one  ouglit  to  siicceed  in  tiiidiiig  ligures 
of  division  of  tlie  riei-ve  fibres  in  ab;  if,  finallj,  a<^b,  Uien,  of 
conrse,  one  onglit  to  be  successful  in  finding  figures  of  growtli  in 
For  the  ventral  root  the  corresponding  line  of  argument  is,  of  conrse, 
as  follows:  if  r/j  = ('i,,  then  there  are  probably  neitlier  fignres  of 
division  nor  growtii  in  the  piece  aj)^  \ if  c/,  ^ tliere  are  probably 
figures  of  growth  in  if  <ib^,  there  are  probably  fignres  of 
division  in 
In  not  a single  case  did  the  calcnlations  that  were  carried  out 
give  values  for  a that  were  greater  than  those  of  b,  nor  val  nes  for 
greater  than  those  of  The  two  values  for  each  root  in  older 
animals  were  — apart  from  the  possibilily  of  error  (about 
2 7o)  — equally  large.  In  young  animals,  on  the  other  hand,  as  a 
rille  aC^b  and  a^'^b^.  As  examples  we  may  give  the  values  for 
S.  I (left  side)  in  a pnp|)y  sixty  days  old  : (ï  = 9209.  6 = 11487; 
a,  = 3335,  b,  = 2623. 
If  we  correct  these  numbers  according  to  the  percentage  of  error 
in  the  calculation,  we  then  obtain : a = 9209  2 "/o  = 9393, 
6 = 11487  — 2 •/.  =11251  ; r/.  = 3335  -2  7„  = 3268,  6,  = 2623 -f 
+ 2 7»=:  2675. 
These  figures  are  very  clear  evidence  against  the  occnrrence  of 
any  figures  of  division  in  the  pieces  ab  and  lï/q  respectively  in  the 
animals  in  question.  On  the  other  hand  they  indicate,  of  conrse,  the 
existence  of  a not  inconsiderable  number  of  ligures  of  new  growth 
of  axons.  As  far  as  I can  see,  I have  found  a sniall  number  of 
certain  figures  of  new  growth  — there  are  undonbtedly  more  of 
these.  These  formations  \ary,  of  conrse,  very  greatly  in  their  forni. 
Siich  great  differences  in  the  number  of  nerve  fibres  in  a and  6 and 
a,  and  6,  are,  however,  not  always  found  even  in  young  animals; 
the  differences  are,  as  a rule,  considerably  less. 
1 could  not  discover  any  possible  method  of  verifying  more  effect- 
ively  the  above-mentioned  absence  of  any  T-  and  F-divison  in  the 
spinal  cord  and  the  spinal  ganglia  of  the  nerve  fibres  that  pass  into 
the  roots.  and  have  conseqiiently  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.) 
