/ EGETABLE PRO TEIDS. 5 ' 
Vegetable proteids. — The amounl of proteid matter in plants, 
especially in those which are full grown, is less than in animals. It occurs 
dissolved in i heir juices, or in their protoplasm, or deposited in the form 
of granules called aleuron grains, l'lant proteids have frequently heen 
obtained in a crystalline form. They may be divided into the same 
classes as the animal proteids. 
Class 1. Allium! n.s. -Small quantities of true albumin have been 
described by S. .Martin ' in the juice of the jjapaw fruit, and by Green 2 
in the latex of several caoutchouc-yielding plants of the natural orders 
Apocynese and Sapotaeeae. 
Class -. Globulins. — These are by far the most abundant natural 
proteids present in plants. This view, which was taken by Hoppe- 
Seyler, 3 is contrary to that of Ritthausen, 4 who regarded vegetable 
proteids as consisting chiefly of legumin and allied substances. 5 
Class 3. Albuminates. — Acid and alkali albumin are formed readily 
from vegetable proteids, especially from plant myosin. Legumin or 
vegetahle casein was used synonymously with vegetable proteid by some 
of the earlier investigators, 6 but it is now usually regarded as alkali 
albumin, formed artificially in the extraction of the globulins by alkali. 
The name conglutin was introduced by Ritthausen 7 for the more 
glutinous product obtained from almonds and lupins. 
Class 4. Proteoses and peptones. — Proteoses have heen described in 
latex, in papaw juice, and flours of different kinds. True peptones arc 
not found in the circulating juices of plants. Probably the circulating 
proteids in plant life are proteoses, hemialbumoses ( Vines), though amido- 
acids (leucine, tyrosine, asparagine, adenine, etc.) 8 also occur. These 
substances are formed by proteolytic ferments during u r ermiiiation. The 
best known of these ferments, papain, has been investigated byWurtz, 
Martin, and others. Such ferments, as well as malting ferments, which 
convert the insoluble starch of the seed into the soluble sugar,are probably 
almost ubiquitous. 9 In carnivorous plants, another ferment is met with 
of a somewhat different character. 
Class 5. Coagulated y/,'e/V,V/.s.— Vegetable albumin and globulin, like 
those of animal origin, are converted at a high temperature into an 
insoluble heat coagulum. 
With regard to the value of vegetable proteids as food, it may be stated that 
as a rule they are not nearly so readily digested as animal proteids. Prausnitz 10 
1 Journ. Physiol., Cambridge and London, vol. vi. p. 336. 
- Proc. Boy. Sue. London, vol. xl. p. 28. 
;; "Physiol. Cliem.," S. 75. 
4 Ztschr.f. Ohem., Leipzig, Ser. 2, Bd. iv. S. 528, 541: vi. 126; Journ. f. prakt. Chem., 
Leipzig, Bd. ciii. S. 65, 78, 193, 27:J. 
5 Ritthausen defends his view in Chem, Centr.-Bl., Leipzig, 1877, S. 567, 578. 
« Einhof, Nem allg. Journ. d. Chem., v. A. Gehlen, 1805, Bd. vi. S. 126, 548. Dumas 
and ( labours, Liebig, and others also examined this substance. 
7 Ibid., Ser. 2, Bd. xxvi. S. 440. 
8 E. Schulze and E. Kisser, Landw. Vcrsuchs Stat., Berlin, Bd. xxxvi. S. 1 ; E. Sehulze, 
numerous papers in Ztschr. f. physiol. Chan., Strassburg. See especially Bd. xii. S. 405. 
9 Gorup-Besanez, Ber. d. deutsch. chem. Gesellsch., Berlin, 1S74, S. 147S ; Krauch, 
Journ. Chem. Soc, London. 1878, Abst. p. 996 ; Green, Proc. Roy. Soc. London, vol. 
xli. p. 466; Thiselton Dyer's Presidential Address, Sect. D, Brit. Assoc, 1888; Hansen, 
Pot. Ztg., 1886, S. 137 ; Ellenberger and Hofmeister, Ccntralbl. f. agric. Chem., Leipzig, 
1888, S. 319. The subject of enzymes and reserve materials in plants, however, is now 
a very large one, and it will be found discussed, with bibliography, in a series of articles by 
J. Reynolds Green, in Science Progress, London, vol. i. p. 342 ; ii. p. 109 ; iii. pp. 68, 376 ; 
v. p. 60. 
10 Ztschr.f. Biol., Munchen, Bd. x.xiv. S. 227. 
