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DEPARTMENT OF GENETICS. 121 



These observations concerning the relation of endocrine glands to the 

 various causes of early embryonic death indicate that many of the disorders 

 of reproduction are traceable to abnormal incretions of the mother. 



Another line of investigation of early embryonic death has been made in 

 cooperation with Mr. Embree R. Rose. This is a study of various elements 

 of nutrition as possible causes of reproductive abnormalities and embryonic 

 death. This work was nearing completion when reported for last year. The 

 final results confirm the statements made at that time — the notable reproduc- 

 tive abnormalities which appear in significant numbers in our birds can not 

 be ascribed to deficiencies of the common and well-known factors of diet. 



A Simple Method for Obtaining Premature Eggs from Birds. 



A paper dealing with this subject has been published by Dr. Riddle. By 

 means of hypodermic injections of small amounts of pituitrin, the eggs are 

 laid in from 4 to 30 minutes after injection. 



By this method eggs at various stages of immaturity, including successive 

 eggs from the same parent, are made easily available for studies on the earlier 

 stages of embryonic development, for experimental studies on these most 

 modifiable stages, for chemical studies on various parts of the egg with less 

 than the usual opportunities for change and admixture, and for isolating the 

 functions of the various parts of the bird's oviduct. It is probable also that 

 under certain conditions or limitations this reaction of the dove's oviduct, 

 living and in situ, would be useful as a means of standardizing solutions of the 

 active principle of the pituitary gland. 



Decrease of Blood Sugar of Pigeons During Prolonged Inactivity and Close 



Confinement. 



This study was made by Dr. Riddle in cooperation with Dr. H. E. Honey- 

 well. It is well known that common pigeons kept confined in small cages 

 usually do not produce eggs. The reason for this has been far from clear. 

 It has, however, been shown by Lusk that dogs kept in the laboratory and in 

 very confining quarters undergo a decrease in their basal metabolism. Since 

 we had already learned that a high mobilization of sugar occurs at ovulation 

 periods in pigeons, we considered it probable that the close confinement of 

 these pigeons brought about a reduction in their metabolism similar to that 

 found by Lusk for dogs, and that this lowered metabolism should express 

 itself in a lowered blood sugar. Three series of tests made on 25 common 

 pigeons show a fall of the blood-sugar value from 180 mg. per 100 c. c. of blood 

 to 126 mg. as the result of three weeks of close confinement. 



Variation and Correlation of Fecundity in the Domestic Fowl. 



For the past several years this Department has had under way a detailed 

 statistical investigation of the various phases of the problem of variation, 

 correlation, and the inheritance of fecundity in the domestic fowl. 



From the practical side, one of the most important results of these investi- 

 gations has been the demonstration that the egg records of various periods of 

 the year are so correlated that it is possible to predict the future egg record 

 or the annual egg record of a bird from the records of short periods of time 

 with a considerable degree of accuracy. This conclusion has been based 

 primarily on studies of the White Leghorn, for which more data are available 



