337 
in the milk of the cow, woman, sheep, goat, pig, horse, and half- 
breed buffalo. By the methods ordinarily employed in the prepara- 
tion of enzymes, these authors succeeded in preparing from the 
fresh centrifuge slime of milk that had been kept continuously in 
contact with chemical antiseptics, aqueous extracts possessing pro- 
teolytic properties to a marked degree. These extracts were also 
observed to have the power of curdling fresh milk, similarly to ren- 
nin, and also of rapidly decomposing hydrogen peroxide. Galac- 
tase has been found to be similar to trypsin in its action on pro- 
teids, converting them into proteoses and peptones and finally into 
amino-acids. Like trypsin it has been found to be most active in 
solutions that are slightly alkaline to litmus, and like all ferments it 
is easily destroyed by heat. 
Some idea of the changes produced in milk by the action of this 
enzyme may be formed from the results of analyses made by Bab- 
cock and Russell of milks that were allowed to stand for various inter- 
vals of time in the presence of an antiseptic to prevent the growth of 
bacteria. These results are given in the following table : 
Description of milk. 
Average of fresh, whole milks analyzed 
Average of whole milks, 20-25 days old 
Average of centrifugal skim milks (fresh) 
Average of centrifugal skim milks, 8-12 months old 
Maximum found in skim milk 
Per cent of 
proteids in 
soluble 
form. 
21. 07 
38. 27 
25.26 
73.30 
91.18 
The proof of the enzymic nature of these changes is shown by the 
stability of milk heated to a sufficiently high temperature to destroy 
such ferments, and by the fact that fresh milks when preserved 
with powerful antiseptics, such as mercuric chloride, formalin, etc., 
undergo no change even though they be kept for indefinite periods of 
time. 
These observations on galactase have been fully confirmed by Von 
Freudenreich (10) and other investigators (11). Wender (12) has 
shown, however, that galactase as ordinarily prepared from separator 
slime, according to Babcock and Russell’s method, in reality consists 
of at least three distinct enzymes, viz, galactase proper, peroxidase, and 
catalase. Ordinarily galactase by itself acts too slowly to cause any 
material change in the proteids of milk in the short intervals which 
usually elapse between the withdrawal of the milk from the animal 
and its consumption as food. It is claimed by Babcock and Russell, 
however, that this enzyme probably assists in those changes which 
ordinarily take place in the ripening of cheese. It is also claimed by 
24907— Bull. 41—08 22 
