324 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



It is seen from the table that 64.96 per cent, of all the dwarf 

 eggs produced were apparently initiated by the presence of yolk 

 in the duct. 



The presence of almost normal chalazae in a few of the eggs 

 without yolk suggests that a yolk may sometimes enter th<: 

 duct, stimulate secretion of chalazae and then be extruded, 

 leaving behind enough chalazae and albumen to furnish the 

 necessary stimulation for the completion of the egg. In a few 

 cases, however, the arrangement of the chalazal threads and 

 albumen envelopes around a blood clot or a lump of hardened 

 albumen make it seem probable that these particles have fur- 

 nished the stimuli necessary to start the secretion of the egg 

 envelopes. 



X. The Relation of Dwarf Egg Production to Other 

 Observed Phenomena of Egg Production which Occu3 

 in Nature or Have Been Experimentally Produced and 

 the Contribution of this Study to Our Knowledge of 

 the Normal Physiology of Egg Production. 



It has already been noted that the six birds autopsied while 

 an egg was in the oviduct or imeediately after one was laid 

 had large empty follicles in the ovary. Five of. them were 

 absorbing yolk through the visceral peritoneum. In two cases 

 the dwarf egg did not contain yolk. This suggested, first, 

 that ovulation or a specific condition of the sex organs imme- 

 diately accompanying it was the essential stimulus for the 

 secretion of the egg envelopes by the duct, or second, that such 

 a specific condition being present the secretion of the egg 

 envelopes was stimulated by the small lumps of hardened albu- 

 men which seemed to be the nuclei of these dwarf eggs without 

 yolk, or third, that a yolk had entered and then been expelled 

 from the duct. 



That neither ovulation nor any condition of the sex organs 

 associated with it is sufficient alone to cause the formation of a 

 dwarf egg is certain. Birds known to have ovulated into the 

 body cavity for a long time, due either to a morphological or 

 physiological (Curtis and Pearl 191 5, loc. cit.) or surgical 

 (Pearl and Curtis 1914, loc. cit.) disturbances, which pre- 



