1890.] Physiology. 379 
PHYSIOLOGY. 
Electrical Phenomena in Human Skin,—Tarchanoff 1 makes 
some interesting discoveries regarding the electrical phenomena in the 
human skin, accompanying the stimulation of sense-organs and different 
forms of pSychic activity. He connects different parts of the skin 
with the galvanometer, e. g., palm and back of hand or of foot, palm 
of hand and outer surface of forearm, latter and axilla, etc. Slight 
tickling of the body surface produces a considerable movement of the 
galvanometer mirror, following a latent period of from one to three 
seconds, and continuing sometimes for several minutes after the stimu- 
lus has ceased. Other stimuli cause similar electric currents, such as 
heat, cold, pain, electric shocks, sounds, such as speaking and hand- 
clapping, sniffing of ammonia and acetic acid vapor, sugar and other 
sapid substances placed upon the tongue, light thrown into the eyes as 
when the eyelids are merely opened to ordinary light. The author 
goes further and finds that merely imagining these sensations, without 
any stimulus of the sense-organs whatever, is sufficient to produce 
analogous galvanic disturbances ; for example, if the individual fancies 
himself to be enduring intense heat, a strong cutaneous current ap- 
pears. Mental processes, such as the multiplication or division of 
numbers, are accompanied by currents varying in intensity according 
to the complexity of the process; thus, arithmetical problems, the 
answers to which may be taken direct from the multiplication table, 
call forth almost no electric change. Expectation of stimuli or of 
questions to be answered causes irregular movements of the galva- 
nometer mirror. Voluntary movements cause changes of an intensity 
proportional to the amount of moyement. Fatigued individuals show 
little or no galvanic effects. 
In all of these cases the portion of the skin richer in sweat glands 
becomes negative to the other portion. The author hence regards 
the current as a secretion current. The results go to confirm the idea 
that nearly every kind of nerve activity, from the simplest to the most 
complex, is accompanied in man by increased activity of the sweat 
glands, and to strengthen Hermann’s view that the current exhibited 
in the contracted human hand is a secretion current, not a negative 
variation of a preexisting muscle current. In explanation of the fact 
of increased sweat secretion accompanying nerve activity, the author 
casually suggests that, inasmuch as the latter causes an increase of 
1 Pfiiger’s Archiv, Vol. XLVI., p. 46. 
