6 So SE CRE TION AND ABSORPTION B 1 ' THE SKIN. 
secretion, when excitation of previously divided nerves is without effect, 
pointing to stimulation of the gland protoplasm by the drug. 
According to Rossbach, 1 small doses act upon the nerve-endings, 
while large doses also affect the gland protoplasm : and some of the 
experiments of Luchsinger, Marine, and Hbgyes, in which pilocarpine 
caused secretion, long after the time necessary for complete degeneration 
of the nerves had elapsed, point to the same conclusion. 
There appears to be no central action by pilocarpine, for Eobillard, 2 
after separating the foot of a cat from the body, with the exception of 
the tibial nerve, obtained no secretion of sweat on injection of pilo- 
carpine into the general circulation : though the nerve was proved to 
conduct, by a profuse sweat caused on asphyxiation. 
Muscarine 3 also acts as a peripheral excitant, but is less active than 
pilocarpine. 
Atropine and duboisine are both antagonistic to pilocarpine and 
muscarine. 
In the cat an injection into a vein of 3 mgrms. of atropine is sufficient 
to make stimulation of the sciatic ineffective : subsequent intravenous 
injection of 10 mgrms. of pilocarpine will cause sweating, though the 
nerve is still without action on excitation. In such a case the atropine 
poisons the nerve-ending, but the gland protoplasm is still excitable and 
responds to pilocarpine. According to Eossbach, 4 a close of 20 to 30 
mgrms. of atropine is needed, in the case of a cat, to paralyse the gland- 
cells to such an extent that subsequent local application of pilocarpine 
is without effect. All glandular apparatus appears to be far more 
sensitive to atropine than to pilocarpine. 
The local paralysing effect of atropine was elegantly demonstrated 
by Aubert. 5 If the palm or finger (carefully cleaned) is pressed on to 
paper sensitised with silver nitrate, the spots of chloride formed at the 
mouths of the sweat-ducts are quite visible. If the experiment is tried. 
after a pad soaked in atropine solution has been tied over a limited 
surface overnight, that surface is found to yield no spots, in contrast to 
the sum amding field. 
Finally, the terminal sweat apparatus is very sensitive to change of 
temperature. Luchsinger 6 has shown that not only cold but excessive 
heating retards the action of the glands. Thus if, on a warm day, one 
hand be held in water at 45' to 50" C. for ten minutes, while the other is 
immersed in water at 15° to 30° C, and exercise is then taken, the hand 
which was in water at the lower temperature commences to sweat at 
once, the other not for some considerable time. In experimental work, 
in which the excitation of nerves is undertaken and the outbreak of 
sweat observed, the greatest caution is necessary to keep the tempera- 
ture of the extremities constant, for with a cold foot a nerve root hold- 
ing sweat-fibres in reality, may be wrongly considered to hold none, if 
the terminal apparatus is depressed by cold. 
That the formation of sweat is a true act of secretion, and not 
merely filtration, is shown by experiments already quoted, in which it is 
noted that after stoppage of the circulation sweat is still secreted on 
1 Arch. f. d. ges. Physiol., Bonn, 1SS0, Bd. xxi. S. 1. - Loc. cif. 
3 Triimpy and Luchsinger, Arch. f. d. ges. Physiol., Bonn, 1S78, Bd. xviii. S. 501; 
Ott and AVood Field, Jour a. Physiol., Cambridge and London, 1878, vol. i. p. 193; 
Hbgyes, loc. cit. 
4 Loc. cit. 5 Lyon med. , 1874. 
6 Arch./, d. ges. Physiol., Bonn, 187S, Bd. xviii. S. 478. 
