CHEMICAL FERMENTS. 581 



from which the air has been exhausted, also under the 

 pressure of three atmospheres, and also when oxygen, 

 hydrogen, or nitrogen are present. According to the 

 more recent investigations made by Leube, the pro- 

 perty of splitting up urea belongs to various other 

 bacteria ; and pure cultivations of the micrococcus urese 

 proved to be inactive when they were freed from living 

 micro-organisms by nitration through plaster. It is 

 possible, therefore, that the ferment isolated by Musculus 

 did not come from bacteria at all (see page 214). 



All the ferments which have been mentioned here are Method of 

 produced by the organs of higher animals, or by lowly 

 organisms, but are not so intimately connected with the 

 life of the producer that it is impossible to isolate and 

 separate the ferments from the living cells ; when this 

 is done the products so separated show the same activity. 

 In the case of numerous ferments such a separation has 

 been already successfully effected, and we may draw the 

 conclusion from analogy that, as regards the separation 

 of the ferments which have not yet been isolated, the 

 difficulties are chiefly technical, and not insurmountable. 

 They are usually obtained by precipitation from their 

 solutions by such means as alcohol, or by carrying them 

 down with precipitates, and then extracting them from 

 the precipitate thus obtained by means of solvents 

 (glycerine, water). The results of chemical analysis 

 have given the following numbers : 



Carbon. Hydrogen. Nitrogen. Sulphur. Ashes. Chemical 



Diastase ... 457 ... 6'9 ... 4t> ... ... 6.1 composition. 



Im-ertin ... 40'5 ... 6'9 ... 9'5 ... ... - 



Emuisin ... 48'8 ... 71 ... 14'2 ... T3 ... - 



Papain ... 52'2 ... 71 ... 16'4 ... ... 



As regards the analyses as yet made, however, it is 

 probable that the ferments were far from pure ; by 

 cleansing them as far as possible, more especially from 

 dextrine and gum-like bodies, Loew* obtained ferments 

 which approach albuminoid bodies in their composition 

 much more than those which had been previously 



* Loew, Pfluger's Arch., vol. 27. 



