Feb. 93,1924 
Lactase in the Alimentary Tract of Chickens 
607 
Tablb I .—Distribution of lactase in the alimentary tract of the chicken 
Number 
of 
Barfoed’s test for monosaccharids. 
Part of the alimentary tract used. 
chickens 
from 
which 
Number 
of 
experi¬ 
ment. 
Unboiled sample. 
Boiled sample. 
organs 
were 
com¬ 
posited. 
I. 
II. 
I. 
j 
II. 
Crop. 
3 
I 
+ 
+ 
_ 
j 
Do. 
3 
j 2 
+ 
+ 
— 
Do. 
6 
3 
+ 
+ 
— 
— 
Proven triculus.. 
4 
1 
— 
— 
Do. 
3 
2 
— 
— 
— 
— 
Do. 
6 
3 
— 
(?) 
— 
— 
Pancreas. 
4 
1 
— 
— 
— 
Do. 1 
3 
2 
— 
*— 
— 
— 
Do.i 
6 
3 
— 
— 
— 
— 
Intestine. 
4 
1 
(?) 
(?) 
— 
— 
Do.; 
3 
2 
— 
— 
Do.i 
6 
3 
— 
— 
— 
— 
Small intestines from five rats. 
1 
l 
4 
+ 
+ ! 
1 
~ f 
— 
DISCUSSION 
Roaf (5) has shown that Barfoed’s copper acetate reagent can be used 
with accuracy in testing the hydrolysis of disaccharids to monosaccharides 
by enzyms if a boiled control is run at the same time and in exactly the 
same manner as the unboiled solution. Preliminary experiments with 
this reagent and with two quantitative reduction methods, the Munson- 
Walker-Bertrand combination and the Allihn method, indicated that 
the qualitative copper acetate reagent could be used most accurately and 
advantageously with this type of solution. The chief disadvantages of 
any quantitative method lie in the fact that the difference in the reducing 
power of lactose and of hydrolyzed lactose is small. Slight errors in 
measurement of solutions might easily make consistent differences in the 
amount of reduction, which might indicate hydrolysis. When the lactose 
is only partly hydrolyzed, the difference in reduction would be still less, 
and when the sugar solution is very dilute the results obtained by the 
quantitative reduction methods can not be considered satisfactory. 
Examination of the table will show uniformly negative reductions in all 
lactose solutions containing the boiled enzym extract. This is a further 
check on the accuracy of the method, the absence of reduction in these 
tubes proving that any reduction taking place in the unboiled extract 
tubes was due only to the hydrolytic action of an euzym and not to any 
other treatment such as the reaction of the solutions or boiling. 
As shown by the table, the unboiled extracts of the crop showed an 
unquestionable reduction of the copper acetate reagent and, consequently, 
the presence of lactase. The unboiled extracts from neither the proven- 
triculus, the pancreas, nor the intestines of the chickens gave any signs 
of reduction, with the exception of three questionable results, which are 
indicated in the table by question marks. These results were questioned 
because, while a very slight brownish coloration was obtained, it was not 
sufficient to be considered a positive test, and at the same time was 
different from the corresponding boiled extracts. Compared with the 
74027—24- 
7 
