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Physiology. — “On function and structure of the trunk dermatoma.” 
IL. Communication made by Prof. C. WINKLER from researches 
in connection with Dr. G. van RIJNBERK. 
In our last meeting a communication was made about experiments 
tending chiefly to elucidate in what manner the function of the 
trunkdermatoma was destroyed. 
These experiments led to the conclusion that in the dermatoma 
a distinction ought to be established between a central area, being 
by itself capable of sensation, and a marginal area, owing its value 
for sensation only to the assistance of neighbouring dermatomata. 
At present the results will be given of a few other experiments, 
that are not only perfectly in accordance with this conception, but 
would even become unintelligible without it; they will supply further 
informations as to the ranging of the trunkdermatomata, which is by 
no means so simple as might generally be supposed. 
If in experimenting on a dog one posterior root or one pair of 
roots (an anterior and a posterior root) of the chest-medulla are cut 
through, without any more, a research into the sensibility of the 
animal made the same or the next day, gives the following result: 
Along the mid-dorsal line sensation has been preserved. Along 
the mid-ventral line 
Fig. 9. Insensible triangle, lying adjacent to the mid-dorsal (dotted area) after 
cutting through one pair of roots. 
an insensible spot is to be found, shaped like a triangle. The basis 
is lying adjacent to the mid-ventral line and is rather broad. The 
top usually does not reach the lateral boundary-line. The triangle 
is encompassed by a narrow hyperalgetic area, which in most cases 
may be pursued until the mid-dorsal line (fig. 9). 
