Does Rearing Chicks in Confinement Affect the Red Cell or Hemoglobin Content of Their Blood?

In order to control all the factors relating to a particular study, it is the common practice to conduct experiments with growing chicks under indoor laboratory conditions. This practice was made possible by the discovery of means of preventing rickets in chicks which do not have access to direct sunlight. It has been observed1 that a severe anemia is more likely to occur in young pigs which are kept under inside conditions, than it is in those which are kept outside. The question naturally arises as to the possible occurrence of an analogous condition in chicks which may influence the results of experimental work conducted under indoor laboratory conditions. The influence of light on blood formation has been the subject of speculation and experimental study during a number of years. The literature on this subject is well reviewed in a recent article by Laurens2. EXPERIMENTAL Three experiments were conducted, involving . . .