ON THE ORIGIN OF DOUBLE- YOLKED EGGS. 



until June, 1911. She was a beautiful example of the breed, but 

 had an unusually large comb. She was a loud and boisterous 

 cackler, and always made a great fuss after laying. Apparently 

 she never exhibited any tendency to set. Although it cannot 

 be stated with certainty that she never laid normal eggs, it is 

 certain that a very large percentage was abnormal. 



The eggs during her last year measured on an average 7.5 cm, 

 in their long diameter, 4.5 cm. in their short. The yolks, always 

 in individual vitelline membranes, were equal in size with an 

 average diameter of 3 cm. They were always in contact, or 

 practically so, and were surrounded by a common jelly mass. 



The records are too meager to show whether there was any 

 rhythm in her laying. On occasion she laid double-yolked eggs 

 on two or even three successive days. Spells of hyperactivity 

 such as these were frequently followed by periods of indolence 

 lasting from one to several weeks. Sometimes she would lay 

 every other day for a period. 



Although the eggs were always large they decreased in later 

 years. Even then laying caused difficulties as evidenced by 

 noises suggestive of struggle. After a period of laying the bird 

 nearly always "moped," hanging her head and refusing to eat. 

 These sick spells were not noticed during the first year or tw r o, 

 although there was never any eagerness for food. 



I have given these details because they may be valuable as 

 clinical symptoms, and because they show that the ovary, which, 

 as we shall see, was abnormal structurally, was so physiologically 

 as well. In fact I am inclined to think that the structural peculi- 

 arities of this organ are a consequence primarily of some physio- 

 logical defect, and that the abnormal spatial relations brought 

 about in this way gave the physical basis for the production of 

 double-yolked eggs. 



THE ANATOMY OF THE OVARY. 



The ovary was removed immediately after the death of the 

 bird and fixed in Zenker's fluid by my brother, R. W. Glaser. 

 The gross appearance as well as numerous details are reproduced 

 in Fig. I, which I made by first printing an outline of the organ 

 through glass on blue-print paper, and after transferring this to 

 bristle board, filling in the necessary minutiae freehand. 



