46 PROTEIDS. 



under which they are formed, and which are known to be hydrolytic 

 in other cases, e.g. the conversion of starch into sugar by the action 

 of enzymes and acids. There is further a certain amount of direct 

 evidence that their formation is accompanied by the assumption of 

 water 1 . Finally there is an increasing amount of evidence, based on 

 analyses of proteids and the peptones which may be formed from 

 them, that the latter contain less carbon, i.e. more hydrogen (?) and 

 oxygen than the former 2 . But this latter evidence is as yet merely 

 suggestive. It is however borne out by analysis of gelatin-peptones 3 . 

 The one important fact in connection with the relationship of the 

 peptones to the mother proteids is that they are, as already stated, 

 products of the decomposition of the latter and of smaller molecular 

 weight, an assumption which is warranted not only by the whole 

 tendency of recent investigation but more especially by the fact that 

 whereas ordinary proteids are non-diffusible peptones, and to a less 

 degree the albumoses, are diffusible. 



According to the views of some observers it is said to be possible to 

 effect a partial reconversion of peptones into the more primary proteids 

 from which they were obtained by means of prolonged heating to 

 140 170, and possibly by means of a dehydrating agent such as 

 acetic anhydride 4 . But little is however definitely known as to the 

 real nature of the products obtained by these means. 



It was at one time stated that when peptones are injected into 

 the blood-vessels, the blood speedily loses its power of clotting after 

 removal from the body 5 . This action is now known to be due to the 

 albumoses with which the peptones were mixed 6 . The clotting may 

 similarly be prevented by the injection of a 1 p.c. NaCl extract of the 

 pharynx and gullet of the leech : the cause of this has not as yet been 

 fully worked out 7 . 



During the pancreatic digestion of proteids some by-product makes its appear- 

 ance which gives a characteristic violet or pink coloration on the addition of 

 bromine, or of chlorine in the presence of acetic acid. The colour is not due to the 



1 Danilewski, Centralb.f. d. med. Wiss. 1880, Nr. 42; 1881, Nr. 4 u. 5. Arch. d. 

 Sci. phys. et nat. T. vii. (1883), p. 150, 425. 



2 Otto, loc. tit. Kiihne u. Chittenden, Zt. f. Biol. xix. 203; xxn. 452. 



3 Tatarinoff, Compt. Rend. T. 97. (1883), p. 713. Hofmeister, Zt. f. physiol. 

 Chem. Bd. n. (1878), S. 299. Klug, Pfliiger's Arch. Bd. XLVIII. (1890), S. 100. But 

 see also Chittenden and Solley, Jl. of Physiol. Vol. xn. (1891), p. 33 on the 

 gelatoses. 



4 Henninger, loc. cit. on p. 44. Hofmeister, Zt. f. physiol. Chem. Bd. n. S. 

 206. Pekelharing, Pfliiger's Arch. Bd. xxn. (1880), S. 196. Kiihne, Verhand. d. 

 naturhist.-med. Ver. Heidelberg, Bd. in. (1885), S. 290. Neumeister, Zt. f. Biol. 

 Bd. xxm. (1887), S. 394. 



5 Schmidt-Miilheim, Arch. f. Physiol. 1880, S. 33. Fano, Ibid. 1881, S. 277. 



6 Pollitzer, Jl. of Physiol. Vol. vn. (1885), p. 283. 



7 Haycraft, Proc. Roy. Soc. No. 231, 1884. Arch. f. exp. Path. u. Pharm. Bd. 

 xvm. (1884), S. 209. Dickinson, Jl. of Physiol. Vol. xi. (1890), p. 566. 



