CHEMICAL NATURE OF SKIN SECRETIONS. 673 
1 to 12. Indigo is sometimes developed in sweat, 1 though whether from 
indoxyl secreted, or as the result of the growth of chromogenic 
micro-organisms, is not certain. 
The sweat of the horse has been studied by Leclerc '-' and Fred Smith. 3 
This secretion normally contains proteids, a fact which may partly account for 
the debilitating effects of profuse sweating in horses. 
Percentage Composition of Sweat of Horse (Fred Smith). 
Alkaline, sp. gr. 1020 ; Water, 94-3776 ; Organic solids, -5288 j Ash, 
5-0936. 
Serum albumin .... -1049 
Serum globulin 
Fat . 
Chlorine . 
Lime 
Magnesia . 
Phosphoric acid 
Sulphuric acid 
Soda 
Potash . 
•3273 
•0020 
•3300 
•0940 
•2195 
Trace 
Trace 
•8265 
1-2135 
Both Leclerc and Smith found urea in the sweat of the horse. 
The sweat of the hippopotamus contains a reddish-brown pigment not yet 
identified. 4 
Buisine 5 has investigated the constituents of that part of the "sweat" of 
sheep which is soluble in water. He found potash soaps of the fatty acids 
from acetic to capric ; urea and ammonium carbonate ; potash salts of malic, 
glycolic, pyrotartaric, oxalic, succinic, lactic, hippuric, benzoic, and uric acids ; 
phenylsulphate of potassium, and traces of leucine and tyrosine. Malic acid 
was previously only known as a vegetable product. 
Of the watery secretion of the skin of amphibians little is known. The 
reaction of the secretion of the " mucous glands " is alkaline, while that of 
the " granular glands," 6 chiefly found on the dorsal surface of the flanks 
and legs, is acid. According to Leydig, 7 acrid substances are secreted in 
addition to mucin, in the case of the tree frog. In the case of the salamander 
and toad, poisonous substances have been separated. 8 
Gratiolet and Cloez 9 state that the poisonous substance in the skin glands of 
the toad and salamander is soluble in alcohol and of the nature of an alkaloid. 
Vulpian 10 and more recently Phisalixand Bertrand n have investigated this 
substance in the case of the toad. The symptoms of poisoning are — paralysis 
1 Bizio, Sitzungsb. d. k. Akad. d. Wissensdh. , Wien, Bd. xxxix. S. 33 ; Hofmann, 
Wien. rrued. JJ'chnschr., 1873, S. 292 ; Bergmanu, St. Petcrsb. med. Ztschr., 1868, 
Bd. xiv. S. 28. 
" Compt. rend. Acad. d. sc, Paris, 1888, tome cvii. p. 123. 
3 Journ. Physio/., Cambridge and London, 1890, vol. xi. p. 497. 
i Weber, "Stud. ti. Saugetliiere, " Jena, 1886, S. 9. 
5 Compt. rend. Acad,, d. sc, Paris, 1886, tome ciii. p. 66; 1887, tome civ. p. 1292; 
and 1888, tome cvi. p. 1426. 
6 Hermann, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 291. 
7 Arch. f. mikr. Anat., Bonn, 1875, Bd. xii. S. 119; and Biol. Centralbl., Erlangen, 
1892, Bd. xii. S. 45S. 
8 Zalesky, Hoppe-Seylers Med.-chem. Untersuch., Berlin, 1866, Bd. i. S. 85 ; Casali, 
Jahresb. u. d. Fortschr. d. Thicr-CJiem., Wiesbaden, 1873, S. 64 ; Fornara, ibid., 
1877, S. 74. 
9 Compt. rend. Acad. d. sc, Paris, 1852, tome xxxiv. p. 729. 
10 Compt. rend. Soc. de biol., Paris, 1854, p. 135. 
11 Arch, dephysiol. norm, et path., Paris, 1893, Ser. 5, tome v. p. 511. 
VOL. I.— 43 
