PHYSIOLOGY: L. S. PALMER 
585 
bone meal, beginning with birds weighing about one-half pound each. 
Several birds reached the period of fecundity on this ration devoid of 
carotinoids, and the yolks of the eggs laid were remarkably deficient in 
color. 
In the second experiment, carried out during the season of 1917-18, 
75 White Leghorn chicks were placed on a practically identical carot- 
inoid-free ration immediately after hatching. None of these birds 
reached maturity, partly, it is believed, because of nutritional diffi- 
culties, and partly, it is admitted, because of a number of unfortunate 
accidents in caring for the birds, which caused the death of the larger 
share of them. 
The nutritional difficulties of the second experiment were overcome 
in the third trial begun in April, 1918, by introducing into the ration 
both pork liver, which is rich in vitamines,^ but devoid of carotinoids,^ 
and a roughage of paper pulp.^ A flock of 50 vigorous, normal White 
Leghorn chickens were raised from hatching to maturity on this modified 
white corn and skim-milk ration. The mature birds were free from 
yellow pigmentation. 
Not only was normal growth secured on this ration, but the hens 
in the flock exhibited normal fecundity. Seventeen of the hens whose 
egg records were kept averaged 52 eggs each during a period of 233 
days. Several had considerably higher records. One hen laid 44 eggs 
during a period of 59 days. 
Especially interesting was the character of the pigmentation of the 
egg yolks. The hard-boiled yolks were colorless but the raw yolks 
had a faintly yellow color. The pigment, however, was neither carotin 
nor xanthophyll. Acetone readily extracted the coloring matter from 
the raw yolks but the pigmented fat which could be obtained from this 
extract failed to give the reduction test with ferric chloride, which I 
have shown^ to be characteristic of carotinoids. Attempts to identify 
the pigment with Barbieri's^ ovochromine or with bilirubin, were not 
successful. 
It was felt that the negative relation between carotinoids and fat- 
soluble vitamine as exhibited by normal growth and fecundity in 
chickens on rations devoid of carotinoids could not be regarded as 
estabhshed unless the carotinoid-free eggs should prove fertile and 
normal chicks be hatched from them. Inasmuch as the cocks and hens 
of the carotinoid-free flock were kept together throughout the experi- 
ment the eggs were presumably fertile. About 90 eggs, in all, were 
incubated at various times. Forty-one livable chicks were hatched 
