ELECTRO-MOTIVE PHENOMENA IN SKIN GLANDS. 68 1 
excitation of nerves; and further, by the fact that by means of atropine 
the secretion of sweat can be stopped in spite of the continued circula- 
tion of the blood. 
It is probably right to conclude that the blood supply is a necessary 
adjuvant to the prolonged activity of the gland-cells, but not the stimu- 
lant to their action, though, according to Levy, 1 secretion is provoked 
upon reinstallation of the circulation, in a limb with cut sciatic, which 
has been long kept anaemic. This effect may possibly be due to the 
mechanical stimulation of the glands by the pulse. 
Levy Dorn 2 placed the hind-limb of a cat in a receptacle within 
which the air pressure could be raised, and found that the secretion 
could overcome a pressure in excess of that in the large arteries. 
Nothing is definitely known as to the existence or not of any 
action of the nervous system upon the sebaceous glands. 
According to Arloing, 3 section of the cervical sympathetic in 
donkeys causes exudation of sebum from the sebaceous glands of the 
skin of the ear, reaching its maximum fifteen hours after section, and 
lasting for sixty-four hours. Stimulation of the peripheral end of the 
nerve also causes secretion from these glands. 
The glands of the skin of the frog undergo periodic contraction and expan- 
sion by means of their muscular sheaths, 4 and have been carefully studied by 
Engelmann, 5 Strieker and Spina, 1 ' and Drasch, 7 in the web and membrana 
nictitans. The spontaneous movements in the case of the web glands are 
stopped temporarily by section of the sciatic, or seventh, eighth, and ninth 
anterior spinal roots. Excitation of the sciatic or reflex stimulation of the skin 
leads to contraction of the glands, as also does direct excitation by vapours of 
chloroform or ether, or by carbonic acid gas. During contraction of the whole 
gland, by its muscular sheath, the lining gland-cells swell, and, according to 
Drasch, in the case of the membrana nictitans, the fifth cranial nerve, on ex- 
citation, causes contraction of the sheath only, while excitation of the sympa- 
thetic causes swelling of the cells. Pilocarpine causes increased secretion by 
these glands. Strieker and Spina advanced a theory of secretion based upon 
observations of these glands, maintaining that, in the act of swelling, fluid is 
sucked in by the cells from the surrounding lymph spaces, and on contraction 
forced out into the lumen ; the theory obviously involves the assumption of some 
valvular structure in the protoplasm, of which Ave know nothing, and furthermore 
has been disposed of by Drasch, who has found that the glands of the mem- 
brana nictitans may secrete freely in stages of immobility of the lining cells. 
In the case of fish — in the eel it has been shown that the secretion of the 
goblet cells of the epidermis and of the club cells (when present) is under the 
influence of the nervous system, but the nerve paths have nut been worked out. 8 
Electko-motive Phenomena in Skin Glands. 
In attempting to demonstrate the existence of currents in the 
uninjured muscles of the frog, du Bois Eeymond 9 discovered that the 
1 Loc. tit. 
2 "Verhandl. d. Berl. physiol. Gesellsch.," Arch. f. Physiol., Leipzig, 1893, S. 383. 
3 Arch, de physiol. norm, etpath., Paris, 1891, Ser. 5, tome iii. p. 241. 
4 Ascherson, Arch. f. Anat. u. Physiol., Leipzig, 1840, S. 15. 
5 Arch./, d. yes. Physiol., Bonn, 1872, Bd. v. S. 498. 
6 Sitzungsb. d. k. Akad. d. Wissensch. , Wien, 1880, Bd. lxxx. Abth. 3, S. 95. 
7 Arch./. Physiol., Leipzig, 1889, S. 96. 
8 Reid, Phil. Trans., London, 1894, vol. clxxxv. p. 319. 
9 "Untersuch. ueber tbierische Elektricitat," Bd. ii. Abtb. 2, S. 9-20. 
