1139 
much stronger outgrow of the dermatomes at the ventral side of 
“the body has a special signification, and cannot be explained only 
by the differences in length of the dorsal and the ventral medianline 
of the body. 
I think I must find the signification of this fact in the physiolo- 
gical relations existing in the ventral side of the body in opposition 
to the dorsal one. It is certainly clear, that each animal receives 
more stimula from the outside world at the ventral side than at 
the dorsal one. The most primitive functions of life as coition and 
suckling of animals occasion irritation at the ventral side. 
“Umklammerungsreflex’” can during a certain period be easily 
brought about with the male frog by a blunt irritation of the 
sternal part of the skin. Respiration gives rise to oscillation 
of the thorax to the front; the intestines of the abdomen stretch 
the skin here and in this way reflectorically give rise to a tension 
of the abdominal muscles. The two extremities of the tractus in- 
testinalis are at the ventral side. Consequently it is clear that exactly 
at the ventral side of the body the usual, normal physiological 
funetions take place. 
But there is still more. The animal that attacks its prey or enemy 
jumps upon them with the ventral side, the mother animal encloses 
her young ones with the ventral side of the body. All vital func- 
tions are performed at the ventral side of the body, the dorsal side 
is of no account. 
Stimulants consequently always react only on this side of the body. 
For this reason the nervous and organic (receptorical) tissue develops 
itself here more energetically, and we find here a greater extension 
of the dermatomes than at the dorsal side. The stronger anatomical 
development is here consequently a result of the increased physio- 
logical function. 
In order to be able to apply the method indicated by me for 
the determination with one experimental animal of several adjoining 
dermatomes, we must be quite certain that the strychnine method 
is in every respect reliable. It might indeed be that the number of 
dermatomes obtained is too great, because the poison has not 
remained local, and an adjoining dermatome has for this reason become 
entirely or partially involved in the hyperreflexion. The fact that the 
strychnine-dermatomes found by Dusser bE BARENNE for the hindleg 
of the dog corresponded with those of WINKLER and vaN RIJNBERK, 
found according to the isolation-method, speaks strongly for the 
fact that the influence of the strychnine remains local. 
