CHEMICAL COMPOSITION AND GENERAL REACTIONS. 115 



exist. 1 It has been shown that pepsin, trypsin, and papayotin, when 

 added to concentrated solutions of albumoses, will cause a precipita- 

 tion of so-called plaste'in, and Sawjalow has announced that he suc- 

 ceeded in coagulating such plasteins by boiling in the presence of 

 acetic acid, which would establish their albuminous nature. 



Berumzone has further shown that an extract of renal tissue will 

 bring about the formation of hippuric acid from benzoyl alcohol 

 and glycocoll. By means of yeast maltase Emmerling could bring 

 about the formation of amygdalin from glucose and amygdalic acid 

 nitril glucoside. 



Emulsin also has been shown capable of synthetic action, etc. 



Further research will s'how whether a reversible action is common 

 to all ferments. 



Chemical Composition and General Reactions. Of the chem- 

 ical composition of the ferments but little is known that is definite. 

 This is owing to the fact that isolation of any one of the ferments in 

 a chemically pure form has thus far not been accomplished. They 

 apparently contain nitrogen, and are usually regarded as albumi- 

 nous substances ; but it is still a matter of doubt whether this is 

 actually the case, and it is possible that the supposition of their 

 albuminous nature is owing to their being contaminated with 

 albumins. 



Like the albumins, they are as a class non-diffusible. They are 

 soluble in water, and can be precipitated from their aqueous solu- 

 tions by salting with ammonium sulphate or by the addition of 

 strong alcohol, and in some cases by normal salt. But here again 

 it is a question whether the ferments themselves are precipitated by 

 the reagents in question or whether they are mechanically carried 

 down by the general precipitates which are formed simultaneously. 



When kept under alcohol for any length of time some of the fer- 

 ments, such as pepsin and diastase, are rendered inactive and are 

 apparently coagulated, while the activity of others, such as the 

 fibrin ferment, remains unaffected. 



Characteristic general reactions, which are common to all fer- 

 ments, are unknown. Formerly it was supposed that they all pos- 

 sessed the power of decomposing hydrogen peroxide, but it appears 

 that this property does not belong to the ferments proper, but to 

 adherent particles of protoplasm. As a matter of fact, it is possible 

 in a number of ferments to destroy this power of decomposing 

 hydrogen peroxide without influencing their specific activity in the 

 least. If pancreatic juice is thus heated to a temperature of 60 C., 

 and then allowed to cool to 40 C., it will be observed that the fluid 

 is still capable of digesting albumins and of inverting starch, while 

 it has lost the power of decomposing hydrogen peroxide entirely. 

 Similar results may be obtained on heating the dry ferments to a 



1 It has recently been shown that trypsin is capable of bringing about the syn- 

 thesis of protamin from its split products, and from those of casein a paranuclein 

 has been obtained by means of pepsin. 



