1145 
the adjoining ones do not take part in it. Indeed if every root- 
bundle oceupies the entire field of the dermatome, how can we 
then imagine, that by trauma of the spinal-cord or the hind-root the 
dermatome partly does not appear. Trauma. of part of the spinal-cord 
or the hind-root would not be injurious, as the unhurt parts were 
sufficient to supply an entire dermatome. 
I am of opinion that the advantage of my method lies in the fact 
that by the strychnine-method I obtain dermatomes that are most 
likely complete and that by touching the hairs with a pencil I can 
entirely localise the stimulants. These two conditions must be satisfied 
in order to obtain any certainty of the division of the radicularia 
in the dermatome. 
Afterwards I followed the method of pe BARENNE, but then first 
moistened that part of the spinal cord that was lying behind the 
anterior or posterior fil. radiculare of a root, after which the spinal cord 
behind the whole root was moistened. Previously towards the head 
and the tail 1, 2, or 3 adjoining roots had been cut. As an example 
I give here fig. 8. I moistened with the cat of this figure of 
Thoracalis 18 the spinal cord behind the anterior fil, radiculare with 
1°/, sulf. strychnine. The hyperreflectory field that I obtained lies 
between the lines 1 and 3. Thereupon I moistened the spinal cord 
behind the whole root. The field then extended posteriously as far 
as line 4. The field I obtained had now become 1'/, times as large. 
Thereupon I cut all the radicularia but one, I left the most posterior 
one untouched. The field that I obtained now, is enclosed by the 
lines 2 and 4. Consequently the central zone would here be between 
the lines 2 and 3 and the edge-zones between 1 and 2 and between 
3 and 4. From this it appears distinctly that one exterior fil. radiculare 
“covers a great part of a root-field, and that the field that is occupied 
by the central radicularia is much smaller. 
One condition that must be satisfied with these experiments, is 
certainly this, that we make our experiment on complete dermatomes. 
For even with the strychnine-dermatomes we are not always fully 
certain of this completeness. Caricature-formation often occurs here 
likewise. At the ventral side e. g. these dermatomes often appear 
imperfectly, and the edge-zone is very often incomplete or absent. 
And it is exactly this edge-zone in which the difference of extension 
is to be found between the field of the entire root and the most 
exterior radicularia. 
At all events the results of my experiments seem to justify the 
conclusion that the dermatome is not a unity but that it is com- 
posed of separate regions of root-bundles, arranged in a cranio- 
74* 
