338 
Snyder (13) that when milk is used in a mixed diet the proteids have 
been found to be from 4 to 5 per cent more digestible than when milk 
is omitted from the diet. This increased digestibility he claims is 
due to the milk enzymes. In this connection, it is of interest to note 
that Hougardy (14) has recently shown that cow’s milk contains a 
ferment or a kinase similar to enterokinase. The author proposes 
to call this ferment lactokinase. This lactokinase has been found to 
accelerate the digestion of proteids by pancreatic juice and loses its 
power to facilitate this change at 73° to 75° C. 
Lipase. — Marfan and Gillet (15) found a lipase in milk capable of 
hydrolysing monobutyrin. Human milk exhibits this property to a 
higher degree than cow’s milk. The former was found to have a 
lipolytic activity of 20-30 on Hanriot’s scale, while cow’s milk shows 
an activity of only 6-8. Gillet (16) has shown that the milk of differ- 
ent animals contains the lipolytic ferment. This ferment withstands 
cold, but is destroyed by heating to 65° C. It is nondialysable and is 
held back by the porcelain filter. It probably hydrolyses the higher 
fats of milk at least to some extent and may possibly account for a 
small part of the acidity of sour milk. 
In this connection Rogers (17) has observed that this ferment is 
present in butter and on standing increases its acidity. 
The so-called salol-splitting ferment . — Nobecourt and Merklen (18) 
observed that human and ass’s milks have the power of hydrolysing 
salol (phenyl salicylate). For a time this hydrolysis was believed to 
be accomplished by an enzyme, to which the name of u the salol- 
splitting enzyme” was given. It was afterwards shown, however, 
by Desmoulieres (19) and also by Miele and Willem (20) that no such 
ferment exists in milk and that this decomposition of salol is in reality 
a saponification brought about by the alkali present in certain milks, 
and that only those milks having an alkaline reaction are capable of 
effecting this decomposition, so that this probably disposes of this 
subject. 
The oxidizing ferments of milk. — Milk contains no true oxidases or 
oxidizing ferments proper. It does decompose hydrogen peroxide, 
however, and in the presence of small amounts of hydrogen peroxide 
or ozonized oil of turpentine it has the power of effecting the oxida- 
tion of a considerable number of easily oxidizable substances. In 
other words, milk contains, catalase and peroxidase. These have 9 
been referred to in the literature by these names ; and also more or less 
indiscriminately by certain writers as the oxidizing ferments of milk 
or superoxidases, and also by some as the indirect oxidases. 
Catalase. — From what is known of the wide distribution of the 
catalases among living things and plant and animal secretions it 
seems probable, although it can not be said to be known absolutely 
