674 
SECRETION AND ABSORPTION BY THE SKIN. 
commencing in the hind-limbs, slowing and final arrest of the heart, and 
constriction of the pupil. Frogs, guinea-pigs, and small birds are killed by- 
injection of the alcoholic extract of the collection of glands forming the 
so-called " parotids " of the toad. The poisonous substance is dialysable, 
and is probably an alkaloid. The blood of toads also contains small amounts 
of this substance, and the serum of a toad will kill a frog if introduced into 
the dorsal lymph sac. 
The slime of fish is secreted by goblet cells in the epidermis, but has been 
little investigated from the chemical standpoint, on account of the great 
difficulty in obtaining it in sufficient quantities, and free from foreign 
substances. The slime of Myxine glutinosa is most easily obtained, and is 
found to contain a mucin-like body, which, however, does not yield a 
reducing sugar on boiling with dilute acid. 1 
The reaction of the skin of the eel and of Myxine is alkaline to litmus, 
but curiously does not affect phenophthalein. A reducing sugar can be 
obtained from the slime of the eel by boiling with dilute acid.- According 
to Alcock, 3 the slime of the Ammocoete larva yields a proteolytic ferment on 
extraction. 
(b) Sebaceous secretions. — Such secretions are formed by prolifera- 
tion and subsequent degeneration of the cells lining the sebaceous 
glands, in which karyokinetic figures are frequent. 4 
These glands are present over the whole surface of the body, with the 
exception of the palms of the hands, soles of the feet, dorsal surface of the 
third phalanges, and glans penis. 
Since it is impossible to collect sufficient quantities of the sebum of 
man for analysis, we have to rest content with analyses of the contents 
of sebaceous cysts, the vcrnix caseosa of the foetus, or the contents of 
dermoid cysts of the ovary. 
Glycerin and cholesterin fats, fatty acids, albumin (casein ?), free 
cholesterin and isocholesterin, with water and salts, are the main con- 
stituents of sebum. 
The following table is taken from Hoppe-Seyler : 5 — 
Contents of a 
Distended 
Sebaceous 
Gland in Man. 
Vernix Caseosa 
of Man. 
Smegma 
Preputii 
of Man. 
Smegma 
Preputii 
of Horse. 
Water ..... 
Epithelium and albumin 
Fat 
Fatty acids .... 
Alcoholic extract . 
Water extract 
Ash 
317-0 
617-5 
41-6 
12-1 
... 
11-8 
669-8 
40-0 
475-0 
150-0 
33-0 
56-0 
528-0 
74-0 
61-0 
499-0 
96-9 
54-0 
1 Journ. Physiol., Cambridge and London, 1893, vol. xv. p. 488. 
2 Reid, Phil. Trans., London, 1894, vol. clxxxv. p. 319. 
3 Proc. Phil. Soc, Cambridge, 1891, vol. vii. pt. 5, p. 252. 
4 Bizzozero and Vasal e, Med. Ghir. Ccntralbl., Wien, 1884, S. 77 and 179. 
5 "Physiol. Chcm.," Berlin, 1881, Th. 4, S. 761. 
