72 MILK AND ITS HYGIENIC RELATIONS 



would do so when a small amount of formalin was added to the 

 methylene blue solution. This solution, which is now very generally 

 known by the name of its discoverer, Schardinger, is also referred 

 to as the F.M.B. solution (that is, formalin-methylene-blue solution), 

 and the reaction as the F.M.B. reaction, and this term will be used 

 here. It is also known as the indirect reductase reaction. 



The literature upon the Schardinger reaction is now nearly 

 as extensive as^ that of the other ferments in milk. This reaction, 

 which appears' to be usually present in cows' milk, occurs only 

 during the first few hours after milking. If the milk is quite 

 fresh, the methylene blue will be reduced by the F.M.B. solution. 

 After some twelve hours this reaction is no longer given, but is 

 gradually replaced by the direct reduction of methylene blue 

 owing to the presence of bacteria. Some observers have stated 

 that the F.M.B. reaction is also bacterial, but this appears not 

 to be the case, since it has been definitely found in milk obtained 

 free from bacteria. This ferment cannot be regarded as having 

 any influence upon nutrition. It acts only when formalin has 

 been added to the milk, and therefore would not act at all in the 

 stomach of an infant. Moreover, its action is entirely destroyed 

 in an acid medium such as that of the infant's stomach. Further, 

 by the time cows' milk has been brought to the infant, the reaction, 

 even in the presence of formalin and an alkaline medium, will be 

 no longer shown. The investigations which have been carried 

 out have failed to detect this reaction in human milk, thus again 

 accentuating the absence of value of this ferment from a nutritional 

 standpoint. 



On the Presence of Catalase. The ferment which is known 

 by this name has the power of splitting hydrogen peroxide with 

 the evolution of oxygen. A vast amount of work has been carried 

 out upon the presence and origin of this ferment in milk, and, as 

 already mentioned, efforts have been made to obtain a standard 

 for the amount of catalase present, so that excess of this substance 

 could be taken as denoting a pathological condition of the milk. 



Catalase in Cows' Milk. As a result of much investigation, it 

 appears that catalase is universally present in cows' milk, although 

 the amount of this ferment which is present, varies within consider- 

 able limits. Catalase is present in most tissues, and is found in 

 large quantities in the blood. It is also formed by a great 

 number of bacteria. These two last sources of catalase at once 

 give possible origins of catalase in milk. It may be present either 

 as a result of nitration from the blood, or may be the result of 

 bacterial contamination of the milk after it has been collected. 

 In market milk this latter source provides the greater part of 

 the catalase content of the milk. 



In order to determine the catalase content of milk as it leaves 

 the udder, it is necessary to investigate the milk immediately after 

 it has been collected. The milk should be free from bacteria. 



