THE ALBUMINOIDS. 71 



two of these substances, which he named semiglutin and hemicollin. 

 Chittenden and Solley l distinguish between proto- and deuterogelatose, 

 and true gelatin-peptone. Paal 2 has obtained similar substances by the 

 use of hydrochloric acid. By the use of Eaoult's method, he gives the 

 molecular weight of gelatin as 878 to 960, and of gelatin-peptone as 352. 



Strong reagents like sulphuric acid, on putrefaction, decompose 

 gelatin with the formation of glycocine, 3 leucine, various fatty acids, 

 glutaminic acid, carbon dioxide and ammonia. The absence of tyrosine 

 should be noted. Schiitzenberger, 4 who has worked with gelatin by the 

 same methods as he used with proteids, considers that gelatin, like 

 proteid, is a compound of urea with certain amido-acids. 



The importance of gelatin as a proteid-sparing food, though it will 

 not replace proteid entirely in a diet, will be considered under " Nutrition." 



Chondrin is the name given to the impure gelatin obtained from 

 cartilage (which see). 



Elastin. Elastin is a material yielded by the yellow fibres of con- 

 nective tissue. It offers great resistance to reagents, and may be pre- 

 pared from the ligamentum nuchse by extracting the finely divided 

 tissue successively with reagents in which it is insoluble, and in which 

 adherent fatty, collagenous, and proteid matters dissolve (boiling water, 

 1 per cent, potassium hydroxide, 5 per cent, hydrochloric acid, alcohol 

 and ether). By this means a substance free from sulphur is obtained. 

 Chittenden and Hart, 5 in some of their preparations, omitted the 

 extraction with potash, and in these a small percentage of sulphur (0*3) 

 was obtained ; this may be due to proteid impurities, or it may be loosely 

 combined in the elastin molecule. Schwartz 6 has also prepared a sulphur- 

 containing elastin from the aorta. 



The following table shows the results of elementary analyses in per- 



Derivatives of elastin. Elastin is gradually and slowly dissolved by 



1 Journ. PhysioL, Cambridge and London, vol. xii. p. 25. 



2 Ber. d. deutsch. chem. Gescllsch., Berlin, Bd. xxv. 



3 On the preparation and estimation of glycocine from gelatin, see C. S. Fischer, Ztsdw. 

 /. physiol. Chem., Strassburg, Bd. xix. S. 164; and Gonnermann, Arch. f. d. ges. 



PhysioL, Bonn, Bd. lix. S. 42. 



4 Compt. rend. Acad. d. sc., Paris, tome cii. p. 1296. See also Buclmer and Curtius, 

 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xix. S. 850. 



3 Ztschr. f. BioL, Miinchen, Bd. xxv. S. 368 ; Stud. Lab. PhysioL Chem., New Haven, 

 vol. iii. p. 19. 



(i Ztsdir. f. physiol. Chem., Strassburg, Bd. xviii. 



7 Ztschr. f. rat. Med., Leipzig, Dritte Reihe, Bd. x. pt. 2. 



8 Gorup-Besanez, "PhysioL Chem.," Aurl. 3, S. 148. 



9 Ztschr. f. pliysiol. Chem., Strassburg, Bil. vi. S. 330. 



