io 4 THE CHEMISTRY OF THE TISSUES AND ORGANS. 
has been further confirmed by Frankel, 1 who finds that pure ampho- 
peptone is also sulphur-free. 
Phosphocarnic acid lias a complicated molecule ; it yields on 
decomposition carnic acid, carbonic anhydride, succinic acid, sarcolactic 
acid, and a strongly reducing carbohydrate. Siegfried compares it to 
nuclein ; but nucleins yield proteid on decomposition ; phosphocarnic 
acid yields carnic acid (antipeptone) instead ; lie suggests the term 
nucleoli for it. The percentage of- this substance in human muscle is 
01-02. In new-born children the muscles contain less (0 to 0"06 per 
cent. 2 
A phosphocarnic acid is also found in milk, but differs from that in 
muscle by yielding fermentation lactic acid instead of sarcolactic acid 
on decomposition. 3 
Kriiger 4 has found that on hydrolysis and simultaneous oxidation by 
means of ferric chloride, phosphocarnic acid gives off carbonic anhydride ; 
no other substance in muscle extracts does this. He therefore looks 
upon it as the material in muscle which during muscular activity gives 
off carbonic anhydride without using up oxygen. This is a conclusion 
that requires serious consideration and renewed research before it can 
be accepted, but it is another indication of the importance of Siegfried's 
work. 
"We now pass to the non-nitrogenous extractives : — 
Glycogen. — This substance may be extracted from muscle by hot 
water 5 ; or by dilute potash 6 ; the latter reagent effects a much more 
thorough extraction. Cramer, 7 using Kiilz's method, found that different 
groups of muscles contain varying amounts of glycogen, but that corre- 
sponding muscles of the two sides of the body contain the same amount. 
In the heart, glycogen is unequally distributed in the different regions 
(Cramer). The average percentage of glycogen in fresh heart muscle 
is, however, about the same as in voluntary muscle, though it dis- 
appears after death (being converted into sugar as in the liver) more 
rapidly than in skeletal muscle. 8 Glycogen also occurs in other 
involuntary muscles. 9 
The glycogen in muscle during life varies in quantity. The following 
are the principal causes of variation : — 
1. Starvation. — The muscle glycogen disappears during inanition, but 
much more slowly than the hepatic glycogen. 10 Luchsinger 11 stated 
that the glycogen of the heart muscle disappears still less quickly, but 
Aldehoff (using Kiilz's method) could not confirm this. 
1 Loc. cii. 
- M. Miiller, Ztschr. f. physiol. Chcm., Strassburg, 1897, Bd. xxii. S. 561. 
3 K. Wittmaack (ibid., S. 567) gives the percentage of nucleoli in human milk as 0"124 ; 
in cows' milk, 0*056, and in goats' milk, O'll. Blumenthal (Virchow's Archiv, Bd. cxlvi. 
S. 65) gives the percentage in cows' milk as 0*05. 
4 Ztschr. f. physiol Ohem., Strassburg, 1896, Bd. xxii. S. 95. 
5 Brucke, Sitzungsb. d. k. AJcad. d. Wissensch., Wien, 1871, Bd. lxiii. Abth. 2, S. 214 ; 
Nasse, Arch./, d. ges. Physiol., Bonn, Bd. ii. S. 97. 
6 Abeles, Med. Jahrb., Wien, 1877, S. 551 ; Kiilz, Ztschr. f. Biol., Munchen, Bd. xxii. 
S. 161. See also Schmelz, ibid., Bd. xxv. S. 180. 
1 Ibid., Bd. xxiv. S. 67. 
8 Boruttau, Ztschr. f. physiol. Chcm., Strassburg, Bd. xviii. S. 513. 
9 In the stomach, Brucke, loc. cii. ; in the plain muscles of gastropods, Chittenden, 
Ann. d. Chcm., Leipzig, Bd. clxxviii. S. 266 ; Bizio, Atti. r. 1st. Venelo di sc, lett. et arti, 
1866, Ser. 3, tome i. 
10 Weiss, Sitzungsb. d. k. Alcad. d. JFisscnsch., Wien, Bd. lxiv. ; Aldehoff, Ztschr. f. 
Biol., Munchen, Bd. xxv. S. 137. 
11 Dissertation, Zurich, 1875. 
