SO-CALLED 'BIOLOGICAL PROPERTIES' OF MILK 81 



After it had been shown that catalase and peroxidase were 

 separate ferments, further difficulties arose because the reaction 

 with guaiacum tincture was found to show two different phases. 

 Some milks gave the reaction at once on the addition of guaiacum 

 tincture, while in other cases it was necessary to add hydrogen 

 peroxide, and for some time it was considered that these different 

 phases were due to two different enzymes, one of which reacted directly 

 with guaiacum tincture and the other did not. Numerous authors 

 have investigated this question from varying standpoints, and 

 there seems no doubt, at the present time, that the reactions are 

 due to the same body. Where the reaction is given directly 

 with milk and guaiacum tincture it is due to the formation of a 

 peroxide or some similar substance in the guaiacum solution, so 

 that the reaction occurs without the addition of the hydrogen 

 peroxide. It has been found that this substance is present in 

 guaiacum tincture which has been allowed to stand for a prolonged 

 period, or has been exposed to the action of certain chemical sub- 

 stances. Thus Kowalewsky showed that the reaction occurred 

 without addition of H 2 O 2 , when old guaiac tincture, which had 

 stood in the light, was used. Bourquelot showed that the addition 

 of hydrogen peroxide to the tincture produced the same result. 

 Further confirmatory work has been carried out by Neumann- 

 Wender (i, 2), Arnost, Waentig (i), and Siegfeld (i). Bach and 

 Chodat have also reached the same conclusion, although using some- 

 what different terminology, and Moore and Whitley, working with 

 vegetable extracts and also with milk, have shown the same. It 

 seems, therefore, evident that only one ferment is concerned in the 

 reaction with guaiacum tincture. 



The work of Storch has already been referred to fully in the 

 summary of this chapter, and in practical work Storch's method of 

 using para-phenylene-diamine is more generally used than that with 

 guaiacum tincture. The latter, in relation to milk, is now chiefly 

 of historical interest. 



In addition to Storch's method, a large number of other sub- 

 stances have been used by different authors to demonstrate the 

 presence of this ferment. One of the better-known solutions is 

 that prepared by Rothenfiisser, who used the hydrochloride of 

 para-phenylene-diamine and also a mixture of guaiacol and para- 

 phenylene-diamine. For further reference to the reagents employed, 

 see Arnold and Menzel, Glage, v. Itallie, Weber, Wirthle, Zink, 

 Chlopin, Utz (2, 3, 4), Siegfeld (i), Kastle and Porch. 



On the Presence of Peroxidase in Milk. Cows' Milk. No observer 

 has failed to detect the presence of peroxidase in cows' milk, even 

 when the milk is collected with such care that it is sterile. Cp. 

 Rullmann (4), and Harden and Lane-Qaypon. 



Human Milk. Raudnitz (i) (1898) failed to obtain the per- 

 oxidase reaction with human milk using guaiacum and hydrogen 

 peroxide ; and he showed that this was not due to any inhibitory 



