sept. 18, 1916 Dwarf Eggs 1027 



active condition except that the five yolks on the ovary were beginning 

 to be absorbed. There were two large empty follicles. (The bird had 

 not laid for five days before death.) The body cavity contained free 

 yolk. This bird had also ovulated into the body cavity and was ab- 

 sorbing the yolks. Whether or not any of the yolk had entered the 

 oviduct and initiated the secretion and then been expelled is not known. 

 None of it remained in the egg. 



Case 27 was found dead where she had hung herself in a feed rack. 

 A dwarf egg was found in the shell gland. This egg is shown in Plate 

 CXIII, figure 1. It contained two drops of yolk surrounded by albu- 

 men, egg membranes, and a thin layer of shell. The body cavity con- 

 tained a yellow liquid which seemed to be a mixture of yolk and serum. 

 The oviduct was in a normal active condition. 



The ovary contained a series of enlarging yolks and ruptured follicles. 

 From the largest one of the latter yolk was dripping. On examination 

 it was found that the stigma or rupture line of this follicle was forked 

 at the end. The follicle had ruptured only along the two short arms 

 of this forked line. The yolk membrane was broken, but remained 

 within the follicle. An examination of the follicles which contained 

 the growing ova showed that three out of four of these had forked rup- 

 ture lines. The follicles removed from this ovary are shown in Plate 

 CXIII, figure 1. The last four (c, d, e, f) show the follicles containing 

 complete ova. Follicles c, d, and / have forked stigmata, while e has a 

 normal straight stigma. Follicle b is the one which contained the rup- 

 tured and nearly empty yolk membrane. It can be seen from the illus- 

 tration that the straight part of the stigma is unbroken, while the forked 

 part is open. In this case it seems clear that the incomplete rupture 

 of the follicle resulted in the bursting of the yolk membrane. A part 

 of the yolk entering the duct furnished the stimulus for the formation 

 of the dwarf egg. The rest of the yolk was being absorbed by the 

 visceral peritoneum. 



C. — EVIDENCE IN CASES WHERE A DWARF EGG FORMS A PART OF A COM- 

 POUND OR A DOUBLE EGG 



a. — COMPOUND EGG OF WHICH ONE PART IS A DWARF EGG 



Recently an abnormal egg was produced by a bird in the Station flock, 

 which gives additional evidence as to the physiological conditions and 

 nature of the stimuli which may result in the production of a dwarf egg. 

 The shell of this egg is shown in Plate CXIII, figure 2. This egg was 

 compound, and the two parts were of quite unequal size. The com- 

 ponent which filled the larger part of the shell contained a normal yolk 

 in a normal membrane but there was a slight tear in this membrane, 

 and free yolk was protruding from this tear. The hole which faced the 

 small component egg was quite small, and little of the yolk had escaped. 



