( 284 ) 



as curdle milk, after having been digested for a few days with hydro- 

 chloric acid at a temperature of 37° C, no longer showed the action 

 of rennet, but had preserved its peptic action. From this it could 

 not but follow that each of these actions depended upon a separate 

 agent. 



Meantime doubts have gradually arisen as to the correctness of this 

 opinion. That there must at any rate be a very close connection 

 between the proteolytic action of pepsin and the enzym of rennet, 

 was made probable by the experience that all enzym-solutions with 

 a proteolytic action, no matter whether they are of animal or of 

 vegetable origin, can also act like rennet. And, as I communicated 

 some years ago in this Academy, and as was afterwards corroborated 

 by Nencki and Siebek, it could also be proved that all kinds of 

 preparations of pepsin, also when a long digestion with hydrochloric 

 acid and a purification as careful as possible had preceded, are able 

 to act like rennet. 



In 1904 there appeared an investigation by Pawlow and Parast- 

 schck '), in which they demonstrated that pepsin and chymosin must 

 be considered as the same substance. These investigators found that 

 in different liquids containing enzym not only the proteolytic and 

 the curdling power are always found side by side, but that also a 

 proportionately greater curdling power corresponds to a greater 

 proteolytic action. That this is not found in some enzym-solutions 

 of commerce appeared to be owing to the presence of other sub- 

 stances; as soon as their effect was destroyed, the proportionality 

 came to light. A solution of rennet, according to Hammarsten 

 prepared by means of carbonate of magnesia from gastric juice, 

 which, in his opinion, no longer contained any pepsin at all, appeared 

 to be a very good digester of albumen, if only the noxious influence 

 of magnesia-salts was taken away. No more was it proved by 

 Hammarsten, — as Pawlow explained — that a pepsin-solution can be 

 freed from rennet by digestion with hydrochloric acid, as the pro- 

 teolytic action had been examined, while the liquid still had an acid 

 reaction; the curdling action, on the other hand, after neutralization, 

 by which the enzym might be easily destroyed. 



Against Pawlow's explanation objections have been raised. Especially 

 two Swedish investigators, Bang 3 ) and .Schmidt-Nielsen '), have 

 defended Hammarsten's point of view. The investigation of Mr. Gewin 



i) Zeitschr. f Physiol. Chemie, Bd. XLU, S. 415. 

 2 ) Zeitschr f. Physiol Chemie, Bd. XLIII, S. 358. 

 •-) Ibid. Bd. XL VI It, S. 92. 

 *) Pflüoer's Archiv. Bd. LXX1X, S. 425. 



