6 BULLETIN 717, U. S. DEPARTMENT OF AGRICULTURE. 
A review of the literature of protein chemistry shows that while in 
general they are of a very complex structure the vegetable proteins 
yield on hydrolysis nearly all of the 16 amino acids which normally 
result from the decomposition of protein material. While all of these 
amino acids supply elements of value for food purposes, the results 
of carefully-controlled feeding experiments show conclusively that 
the dietary value of the different amino acids varies materially. 
No résumé of the literature of protein and amino acid chemistry 
would be complete without special reference to the extensive investi- 
gations of Osborne’ to whom the present interest in this subject is 
in no small measure due. In this brief discussion of amino acids it is 
impossible to more than refer to the investigations which have been 
carried out by Osborne. et al.,27 Henderson and Dean,? Kauffmann,‘ 
Cohnheim,® Abderhalden and coworkers,’ Henriques,’ Willcock and 
Hopkins,? Miller, Rona and Miiller,’? Michaud," McCollum et al.,” 
Folin and Denis, Hart and assistants,’ Kajiura,’* Wheeler, 
Underhill,” Nollau and Kastle,'* Johns,'® and Geiling,” to determine 
1 Amer. Chem. Jour., 13 (1891), pp. 327-347, 385-414; 14 (1892), pp. 212-224, 629-661, 662-689. Amor. 
Chem. Jour., 19 (1897), pp. 236,237. Jour. Amer. Chem. Soc., 16 (1894), pp. 633-643, 703-712, 757-764; 17 
(1895), pp. 429-448, 539-567, 587-603. 19 (1897), pp. 525-532. Ztschr. Physiol. Chem.,33 (1901), pp. 225-239, 
240-292. Amer. Jour. Physiol., 5 (1901), pp. 180, 181. Jour. Amer. Chem. Soc., 24 (1902), pp. 140-167. 
Proc. Soc. Expt. Biol. and Med., 5 (1908), pp. 105-107. Science, n. ser., 28 (1908), pp. 417-427. The Vege- 
table Proteins [London], Longmans, Greenand Co.,1909. Ergeb. Physiol., 10 (1910), pp. 47-215. 
2 Jour. Amer. Chem. Soc., 16 (1894), pp. 778-785; 18 (1896), pp. 536-542, 542-558, 575-582, 583-609, 609-623; 
19 (1897), pp. 454-482, 482-487, 487-494, 494-500, 509-513; 20 (1898), pp. 348-362, 362-375, 393-405, 406-410, 
410-419, 419-428; 22 (1900), pp. 379-413; 25 (1903), pp. 323-353, 474-478, 837-842, 842-848, 848-853, 853-855. 
Amer. Jour. Physiol., 13 (1905), pp. 35-44, 436-447; 14 (1905), pp. 151-171, 259-286; 15 (1906), pp. 333-356; 
17 (1906), pp. 231-265; 18 (1907), pp. 123-128, 295-308; 19 (1907), pp. 53-60, 117-124, 468-474, 475-481; 20 (1908), 
pp. 470-476, 477-493, 494-499; 22 (1908), pp. 362-372, 423-432; 23 (1908), pp. 180-200. Jour. Biol. Chem., 3 
(1907), pp. 213-217, 219-225; 5 (1908), pp. 187-195, 197-205. Amer. Chem. Jour., 15 (1893), pp. 392-471. 
Jour Biol. Chem., 10 (1911), No. 10, pp. 303-325; 12 (1912), No. 3, pp. 473-510, figs. 26; 13 (1912), No. 2, pp. 
233-276, figs. 21; 14 (1913), No. 5, pp. 481-487; 17 (1914), No. 3, pp. 325-349, figs. 8; 18 (1914), No. 1, pp. 1-16, 
figs. 6; 20 (1915), No.3, pp.-351-378, fig. 10; 22 (1915), No. 2, pp. 241-258, fig. 1; pp. 259-280; 25 (1916), No.1, 
pp. 1-12, figs. 4; 29 (1917), No. 1, pp. 69-92, fig. 1. 
3 Amer. Jour. Physiol., 9 (1903), No. 6, pp. 386-390. 
4 Arch. Physiol. [Pfliiger], 109 (1905), No. 9-10, pp. 440-465. 
5 Hoppe-Seyler’s Ztschr. Physiol. Chem., 49 (1906), No. 1, pp. 64-71. 
6 Hoppe-Seyler’s Ztschr. Physiol. Chem., 47 (1906), No. 4-6, pp. 354-358; 51 (1907), p. 232; 77 (1912), No.1, 
pp. 22-58; 81 (1912), No. 4, pp. 323-328. Synthese der Zellbaustine in Pflanze und Tier. (Berlin, Julius 
Springer], 1912, p. 128. 
7 Hoppe-Seyler’s Ztschr. Physiol. Chem., 49 (1906), No. 2-3, pp. 113-123; 60 (1909), No. 2, pp. 105-118. 
8 Jour. Physiol., 35 (1906), No. 1-2, pp. 88-102. 
9 Arch. Physiol. [Pfluger], 112 (1906), No. 5-6; pp. 245-291, pls. 2, fig. 1. 
10 Hoppe-Seyler’s Ztschr. Physiol. Chem., 50 (1907), No. 4-5, pp. 263-280. 
u Ztschr. Physiol. Chem., 59 (1909), No. 5-6, pp. 405-491. 
12 Amer. Jour Physiol., 29 (1911), No. 2, pp. 215-237. Jour. Biol. Chem., 19 (1914), No. 3, pp. 323-333; 2. 
(1915), No. 1, pp. 181-230, figs. 42; 20 (1915), No. 3, pp. 415-428, figs. 12; 28 (1916), No.1, pp. 153-165, figs. 10, 
No. 1, pp. 211-229, figs. 17; No. 2, pp. 483-500, pl. 1, figs. 12. 
13 Jour. Biol. Chem., 11 (1912), No. 1, pp. 87-95. 
14 Jour. Biol. Chem., 13 (1912), No. 2, pp. 133-153, figs. 4; 19 (1914), No. 3, pp. 373-395, pl. 1, figs.11. Wis- 
consin Sta. Research Bul. 17 (1911), pp. 205, pls. 19. Jour. Biol. Chem., 25 (1916), No. 2, pp. 239-260, pls. 9, 
figs. 9; 29 (1917), No. 1, pp. 57-68, pl. 1. 
15 Bio-Chem. Jour., 6 (1912), pp. 171-181. 
16 Jour. Expt. Zool., 15 (1913), pp. 209-223. 
17 The Physiology of the Amino Acids, F. P. Underhill, New Haven: Yale Univ. Press, 1915, pp. 169, pl. 
1, figs. 13. 
18 Amer. Jour. Physiol., 39 (1915-16), No. 2, pp. 162-171, pls. 8. Kentucky Sta. Bul. 197 (1916), pp. 21, 
pls. 16. 
19 Jour. Biol. Chem., 28 (1916), No. 1, pp. 59-65, 67-75, 77-87. 
20 Jour. Biol. Chem., 31 (1917), No. 1, pp. 173-199. 
