CASEASE 169 



Certain plants, for example, contain it. In certain parts of the 

 country Galium veruni is used to clot milk for cheese-making. In 

 the Italian Alps Pinguicula vulgaris (butter wort) is used in a 

 similar manner (Pfeffer). The secretion of the glands of Drosera 

 clots milk, and so also do the juice of the papaw and the pine 

 apple. Generally speaking it is the fruit and seed of a plant 

 which contains rennet. The ferment has also been obtained from 

 bacteria. In 1852 Haubner found that milk would coagulate under 

 certain conditions without previous acidification, without lactic 

 fermentation, and without the addition of rennet as such. Thirty 

 years later Duclaux studied this matter and finally showed that 

 s,uch coagulation was due to micro-organisms which had the 

 capacity of producing rennet themselves. Wood has isolated the 

 proteolytic ferments produced by a variety of bacilli, and he found 

 in many cases that rennet was also present. Vignat has shown 

 that rennet exists in the B. mesentericus vulgatus side by side with 

 four other enzymes. Conn working in 1892, forty years after 

 Haubner, was able to isolate rennet from bacterial ferments as 

 follows. He clotted milk with the organisms in question, then 

 broke the clot down and mixed it with distilled water, and filtered 

 the whole through porcelain. Then he added sulphuric acid till 

 the whole liquid contained • i per cent, acid, and it was then satu- 

 rated with sodium chloride, A white granular scum rose to the 

 surface which was found to consist of rennet. Rennet was most 

 plentifully secreted when the temperature of the cultures was 

 about 20° C, and the proteolytic ferments preponderated at 

 35' C. \^ 



Flii^ge has placed the peptonising bacilli of milk under a 

 systematic classification. He differentiates four anaerobic bacteria 

 (of the Rauschbrand groW)), one anaerobe with terminal spores 

 (Tetanus group), and elevai other anaerobes whose spores, with 

 one exception, withstand twoi hours' boiling. 



(ii.) Casease is the second body of this group to which brief 

 reference must be made. Ivot infrequently the ^coagulation of 

 casein effected_by such bacteria disappears again after a short 

 tjme^ Duclaux ^ ascertained that this new alteration is due to a 

 second (albumin-dissolving) ferment, to which he gave the name 

 of Casease. It acts not only on the clot but on the unchanged 

 casein of milk, and is of the nature of trypsin. The same observer 

 also discovered, in the case of several species of Tyrothrix isolated 

 from Cantal cheese, certain bacteria gifted with the faculty of 

 * Le LcUt, 1894, p. 113. 



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