120 CAKNEGIE INSTITUTION OF WASHINGTON. 



(6) The relation of the pituitary and its parts to growth, time of maturity, 

 and phenomena of reproduction and sex (with Mr. J. R. Spannuth). The 

 oral administration of the various preparations of this gland have little or no 

 measurable effect on the growth curve. Injections of the extracts of anterior 

 and posterior parts of the pituitary body have been made and growth curves 

 obtained. Data for maturity and reproduction are not yet complete. This 

 is practically the only type of study of this important gland which can be 

 easily made on the pigeon. 



Influence of Incretions of the Mother upon Embryonic Deaths of the Offspring. 



A knowledge of the complete genetic output of a pair of pigeons presupposes 

 that all of the number of eggs laid shall be known and that these shall in 

 nearly all cases be hatched and reared. But in certain parts of our recent work 

 with pigeons very large numbers of young are lost, owing to infertility, early 

 cessation of development, death of embryo, etc. These developmental fail- 

 ures constitute one of the greatest obstacles to progress. During the past 

 year important progress has been made in determining their cause. 



Thus, it appears that some pigeons retain for variable, but abnormally 

 prolonged, periods a small proportion of their eggs in the shell gland of the 

 lower oviduct after the shell material has been placed upon the egg. Such 

 egg-shells usually have an abnormal thickness, and they develop abnormally. 

 The delay may reach the extreme of 100 hours. When it exceeds 20 to 24 

 hours, the developing germ usually dies at the one-half day stage. From a 

 delay of 24 to 50 hours an embryo occasionally survives. 



As stated below, such delayed eggs are easily forced from the oviduct by 

 the administration of pituitrin, and it is possible that the failure to expel the 

 egg is due to disfunctioning of the bird's pituitary gland. 



In a third series of cases evidence has been obtained which indicates that 

 death of the embryo sometimes results from the very early break or rupture 

 of an inefficient vitelline membrane. The eggs of only a few birds exhibit 

 this characteristic, but it is usually exhibited by several or many of the eggs 

 of a particular bird. The rupture and death occur most commonly at the 

 one-day or two-day stage. After a real rupture of the yolk-membrane, and 

 after significant outflow of yolk, continued life in the embryo is impossible. 



In a fourth group of cases, series of embryos from the same parents are found 

 dead at the three-day to four-day stage, and, though these embryos seem 

 otherwise normal, the amnion has failed to complete its development and the 

 incompletely inclosed embryo has become adhered to the shell. Dr. Riddle 

 concludes that, though our evidence is not conclusive on the matter, the initial 

 failure is that of the development of the amnion and that adhesion to the 

 shell and resultant death are subsequent events. Data concerning the more 

 remote basis of the improper development are being collected. 



A fifth group of cases is formed by those ova which are not received into 

 the oviduct, but pass into the body-cavity and there fail to develop. It has 

 been shown that the injection of small amounts of pituitrin (the active prin- 

 ciple of the pituitary gland) during the first few hours after the entrance of 

 an ovum into the upper oviduct will usually cause this j'-olk to be returned 

 to the body-cavity. These results suggest that a temporary hypersecretion 

 of the pituitary gland by the mother bird may be the cause of these ovula- 

 tions into the body-cavity. 



