THE DECOMPOSITION PRODUCTS OF PROTEID S. 29 
prepared synthetically. 1 Tyrosine (< ! 9 H u N0 3 ) is oxypheny] amidopropionic 
acid, 1I().<', ; II,<'_.H (Nil i.rooii. This substance has also been made 
synthetically. 2 The crystalline tunas of these two substances are seen in 
the accompanying figures (Figs. 7 and 8). Aspartic or asparaginic acid 3 
(C 4 H 7 N0 4 ) is amido-succinic acid. C 2 H 3 | Nil x( !< M »II )_. Thai ammonia 
is produced in prolonged pancreatic digestion, under conditions preclud- 
ing the possibility of putrefaction, was shown by Stadelmann. 4 
To this list must lie added lysine, lysatinine, arginine 6 (see p. 
33), glutaminic acid, ami proteinchromogen, 6 a substance of un- 
certain nature which gives a reddish-violet product with chlorine or 
bromine water. 
Within the intestine many changes occur which are due to bacterial 
action. The products which have just heen enumerated arise first, 
and then by different changes other substances are tunned; of these 
the following may he mentioned: — indol, skatol, skatol-carbonic acid, 
oxyphenylpropionic acid, phenylpropionic, and phenylacetic acids, 
parakresol, and phenol, and simpler bodies like carbonic anhydride, 
water, ammonia, hydrogen, and sulphuretted hydrogen, amido-fatty acids, 
and fatty acids themselves. 7 The most interesting point to note here 
is the large number of derivatives containing the benzene nucleus. The 
indol group has never heen obtained from the proteid molecule by any 
other method than that of bacterial decomposition. 8 
We can now pass to the second category of investigations, namely, 
those carried out in vitro. 
The first action produced by most reagents, especially if they bring 
about hydrolysis, is the formation of proteoses and peptones : these are 
then broken up into more simple substances. The subject may be most 
conveniently treated of under the heads of the different methods empL >yed. 
1. Treatment with alkalis. — Mulder 9 treated albumin with caustic 
potash, and obtained the substance which we now call alkali-albumin; 
this material is free from most of the sulphur present in the original 
proteid, namely, that which is present in loose combination ; the firmly 
combined sulphur, however, remains undisturbed. 10 
Mulder thought that by this method he had obtained the base of 
all albuminous material, and called it "protein"; he described many 
1 For recent literature on leucine, see Schulze and Likiernik, Ztschr./. physiol. Chem. 
Strassbnrg, Bd. xviii. ; Gmelin, ibid., Bd. xviii.; HiU'ner, "Synthesis of Leucine," Journ. f. 
prakt. Chem., Leipzig, X. F., Bd. i. : E. Schulze, Barbieri and Bosshard, Ztschr. f. physiol. 
Chem., Strassbnrg, Bde. ix. and x. ; Colin, ibid., Bd. xx. 
- Erlenmeyer and Lipp, Ber. d. dcutsch. chem. Gesellsch., Berlin, Bd. xv. S. 1544. 
: For chemistry and preparation, see Hlasnvetz and Habemiann, Ann. d. Chem., 
Leipzig, Bd. clxix. S. 160 ; E. Schulze, Ztschr. f. physiol. Chem., Strassburg, Bd. ix. 
* Ztschr. f. Biol., Miinchen, 1888, Bd. xxiv. S. 261. See also Hirschler, Ztschr. f. 
physiol. Chem., Strassburg, Bd. x. S. 302. 
' 5 Hedin, Arch. f. Physio/., Leipzig, 1891, S. 273. 
6 Stadelmann, Ztschr./. Biol., Miinchen, Bd. xxvi. S. 491. Neumeister suggests the 
name tryptophan for this substance, ibid., S. 324 ; Nencki, lu r. d. dt utsch. chem. Gesellsch., 
Berlin, Bd. xxviii. S. 560. 
7 Salkowski, ibid., Bd. xii. S. 648; Tappeiner, Ztschr. f. Biol., Miinchen, Bd. xxii. 
S. 236. 
8 For recent work on the mycological processes in the intestines, see V. D. Harris, 
Journ. Path, and Bacteriol., Edin. and London. 1S95, vol. iii. p. 310. On the putrefaction 
of pure proteids see 0. Emmerling {Ber. d. dcutsch. chem. Gesellsch., Berlin, 1896, Bd. xxix. 
S. -721) : in addition to the substances enumerated above he finds betaine. 
9 Journ. f. prakt. Chem., Leipzig, Bd. xvi. S. 129; Bd. xvii. S. 312; Ann. d. Chem., 
Leipzig, Bd. xxxi. S. 129. 
lu Kruger, Arch. /. d. ges. Physiol., Bonn, Bd. xliii. S. 244. 
