PROTEOLYTIC ENZYMES. 301 



test for determining the relative strength of two solutions of a 

 proteolytic enzyme, since the amount of gelatin dissolved per unit 

 of time under identical conditions may be regarded as a measure of 

 the concentration or potency of the samples. If tubes of equal 

 diameter are used, then this relation is simply expressed by the 

 height (thickness) of the two liquefied strata. Fermi claims that 

 his method is more reliable than those proposed (for the same 

 purpose) by Griinhagen, Griitzner, Briicke, and Schiitz, and which 

 consist chiefly in determining the amount of fibrin dissolved by the 

 sample under certain definite conditions. As we have already 

 mentioned that this latter substance is attacked with greater diffi- 

 culty than gelatin, it will be at once evident that Fermi's method 

 is the more delicate. 



With regard to casease, i.e. the enzyme decomposing the 

 casein of milk into soluble products, the chief particulars have 

 already been given in 147. Many bacterial species are, however, 

 capable of dissolving this albuminoid without any trace of casease 

 being found in the cultures. One of these is the Bacterium pepto- 

 faciens, isolated from milk by AL. BERNSTEIN (I.), which is particu- 

 larly active in converting casein into peptone and albumoses, a 

 little (0.2 per cent.) lactic acid being also formed. If, now, the 

 milk be boiled after the bacterium has been in action for a short 

 time, the unconverted casein will be thrown down, and, when 

 filtered off, leaves behind a liquid which is rich in readily digestible 

 peptones, and has been named "galactone" by its inventor. The 

 milk-sugar present in this liquid may be fermented by the addition 

 of suitable yeasts, and then yields "galactone wine." 



The bacteriological researches of the past few years have resulted 

 in an important modification of the opinions held regarding the 

 so-called carnivorous plants. According to earlier statements, the 

 glands of the parts of the plant acting as a snare secreted a dis- 

 solving albumin enzyme, which digested the captured prey, i.e. 

 converted its albuminoids into assimilable peptones, &c. Hoppe- 

 Seyler in 1876 threw doubts on the presence of this enzyme in 

 Drosera rotundifolia, and in 1889 N. TISCHUTKIN (I.) ascribed the 

 phenomenon to bacterial activity. 



This observer ascertained that the juice collecting on the sur- 

 face of the leaves of Pinguicula is rendered inactive by painting 

 the leaves over with bactericidal media. The same conclusion was 

 arrived at by R. DUBOIS (II.) in 1890, in his experiments on the 

 contents of the urns of Nepenthes; and two years later the matter 

 was again examined by TISCHUTKIN (II.) in the following plants : 

 Drosera rotundifolia, L., D. Longifolia, L., Dioncea muscipula, 

 Ell., Nepenthes Mastersi, the results confirming the hypothesis 

 expressed above, viz., that the digestion of the albuminoid bodies 

 falling or introduced into the juice excreted by these plants is 

 exclusively due to the activity of bacteria settling in the said 

 liquid and there producing a proteolytic enzyme. According to 



