422 
Journal of Agricultural Research voi. xxvii, No. 6 
fined oil is richer in the fat-soluble factor than the refined oil, we can 
readily account for these facts by assuming that the liver is also richest 
in manganese; the crude oil would contain less manganese than the liver 
but more than the refined oil. In the process of refining the crude oil 
it is filtered through fuller’s earth until the oil which was dark in color be¬ 
fore filtering is changed to a golden straw color. It is apparent that the 
fuller’s earth removes by adsorption most of the vitamin factor A, which 
in all probability is a colloidal form of a manganese compound. This 
assumption is further supported by the fact that Seidell ( io ) has made 
use of fuller’s earth as a means of separating, by adsorption, some of 
the vitamin factors. However, he has neither shown nor suggested that 
it was a compound of manganese that was being adsorbed by the fuller’s 
earth. 
MANGANESE IN FISH ROE 
One pound of fish roe was purchased at a fish market in Lexington, 
Ky., dried at no° C., and ioo gm. of the moisture-free material ashed 
for a manganese determination. Three parts per million of manganese 
was found in the moisture-free roe of the fish. The livers from fresh¬ 
water fish, newlights, were obtained from the same market, and 3.75 
parts per million of manganese was found in the dry material of the 
fish livers, which is considerably less than the amount found in the livers 
of domestic animals. Other investigators state that the flesh of fish is 
poor in vitamins, whereas their roes and livers are rich in these factors, 
a fact in harmony with the findings of the author in regard to man¬ 
ganese content. 
MANGANESE IN MILK 
Some investigators state that milk is richest in vitamins at the begin¬ 
ning of the lactation and that its vitamin potency diminishes as lactation 
progresses. To determine whether the manganese content changes in 
a similar way, samples were obtained from the first colostrum of a normal 
cow of the station herd, taken before the calf had sucked, and from the 
milk of the same cow a month later. Each sample was analyzed by 
evaporating 1,000 gm. to dryness, ashing and determining manganese in 
the ash. The results are as follows: 
Colostrum, Milk, 
Apr. 17,1923* May 17,1923. 
Percentage of ash. 1.154 0.711 
Mn. in the ash, parts per million. 20 4 
Mn. in the milk, parts per million. .2 .03 
The falling off in manganese content is very marked. If manganese 
is responsible for vitamin potency, the decline of the latter should be in 
a similar degree. These findings suggest that manganese is mobilized 
during the time the cow is not producing milk, presumably for the pur¬ 
pose of supplying an element that has important functions to perform 
during a critical period in the life of the young offspring. 
MANGANESE IN THE YOLK OF EGGS 
Another source of the fat-soluble A vitamin is the yolk of eggs; the 
white of the egg has proved to be devoid of vitamins. 
One dozen fresh, viable eggs were obtained from the poultry farm of 
the station and hard boiled in distilled water. The eggs were then 
separated into three parts, shell, whites, and yolks. The whites and 
