1058 The American Naturalist. [December, 
ing, without any distinct physiological basis at all. The use of a single 
term in English for both Schmerz and Unlust has tended to obscure 
their difference, but recent discussion has brought it out with greater 
distinctness, and many writers now regard pain—at least when it in- 
volves some definite locality, as in the case of head-ache, tooth-ache, 
pricking, etc.—as a real sensation. 
Attempts have been made, in connection with this view, to discover 
definite end-organs and nerve tracts for the pain sense. The probabil- 
. ity of the existence of such a physical basis has lately been urged with 
great force by a number of writers, on the evidence furnished by cer- 
tain pathological cases, where laino hyperalgesia or analgesia 
occur without any marked alteration in the senses of pressure or tem- 
perature. They argue that if pain can be heightened or deadened 
without disturbance of the other dermal senses, it must be furnished 
with a distinct sensory apparatus of its own. Numerous clinical cases, 
reported by Dr. Henry Head in a series of articles in “ Brain,” ë lend 
considerable support to this view. These observations and others 
have been regarded as direct evidence that pain has a distinctive 
anatomical and physiological basis—either a complete set of end- 
organs and nerve apparatus, or at least a separate conducting tract 
and cortical center. Several objections have been raised against the 
more radical view, the chief being that no type of end-organ has been 
found in the skin, apart from those required for the senses of pressure 
and temperature. 
A recent paper by Prof. Witmer, of Pennsylvania, reported at the 
British Association this summer and since published,‘ recognizes the 
force of this criticism, and favors the modified view of a spinal tract 
and center for pain. Prof. Witmer reviews the clinical and experi- 
mental evidence in great detail, taking up the parts of the sensory ap- 
rE separately. 
ere is no conclusive anatomical evidence,” he says, “ for the ex- 
istence of a peripheral sense organ or nervous end organ for pain. 
There is no conclusive evidence for the existence of peripheral pain 
nerves or peripheral sensory neurons. Much evidence justifies the 
conclusion that all or some peripheral nerves may, under adequate 
stimulation, act with specific pain-producing function ; that such nerves 
may lose this function without a loss of other functions or may lose 
their other specialized sensory functions without losing the pain func- 
tion. Local peripheral analgesia and mR due to compression or 
< 3 Vols. XVI, p. 1; XVII, p. 339, and XIX, 
* Twentieth Century Practice of Medicine, Ah eA p. 905. 
