PHYSIOLOGY: W. B. CANNON 
319 
STUDIES OF DUCTLESS GLANDS BY THE ELECTRICAL 
METHOD 
By W. B. Cannon 
LABORATORY OF PHYSIOLOGY. HARVARD UNIVERSITY 
Read before the Academy. April 17. 1916. Received, May 2. 1916 
A study of the conditions of activity in the ductless glands, which 
pass their secretions into the blood stream, is difficult because recogni- 
tion of the secretion in the blood is uncertain or impossible. It has 
long been known that physiological activity is accompanied by the de- 
velopment of an electrical difference which may be manifested by con- 
necting an active part with an inactive part through a delicate gal- 
vanometer. It seemed possible that by the application of this method 
important information might be obtained as to the conditions of activ- 
ity of the ductless glands. This work has been carried on through the 
cooperation of Mr. McKeen Cattell. 
The method was first justified by applying it to the submaxillary 
gland which has an external secretion. Because an electrical change 
accompanies the secretion of saliva even though the blood supply is 
shut off from the gland or the flow through the duct is stopped ; and be- 
cause the change is absent when secretion is absent, although each of 
the conditions attendant on secretion (such as contraction of blood 
vessels, relaxation of blood vessels, faster flow of blood, slower flow of 
blood) may severally be induced, the conclusion is drawn that the elec- 
trical change is a manifestation solely of the process of secretion. 
The direction of this electrical current of action developed by the 
submaxillary gland may be reversed although the physiological responses 
to stimulation remain as usual. Reversal is not, therefore, a certain 
sign of a reversed physiological process in the gland. 
When the action current indicates a maximal activity of the sub- 
maxillary gland excited by stimulating the sympathetic nerve in the 
neck (cat), the electrical response can be augmented by stimulating the 
chorda tympani nerve and vice versa; sympathetic impulses are in- 
effective during the height of an effect produced by injected adrenin, 
and chorda tympani impulses cause no increase of the action current 
while pilocarpine is strongly operative. 
The method thus justified on the submaxillary gland has been applied 
to the thyroid. Histologists have described nerve fibers leading to the 
cells of this gland, and anatomists have reported that the fibers going 
to the thyroid gland arise in the cervical sympathetic ganglia. Previ- 
ous investigators have shown that severance of its cervical sympathetic 
nerves causes atrophy of the thyroid, and stimulation of these nerves 
