112 RAYMOND PEARL AND WILLIAM FREEMAN SCHOPPE 



surface of the ovary. Other experiments had indicated that by 

 inducing regeneration of the ovary a bird could be caused to lay 

 more eggs than she would have had there been no interference 

 with the ovary. The present experiments were undertaken as 

 a quantitative test of this suggested result. 



Eight birds were used in the experiments, four Barred Plym- 

 outh Rocks and four Cornish Indian Games. The operation 

 protocols follow: 



Bird no. 9017, operation 131. Bird in find condition, large 

 yolks being absorbed; about five-sixths of the ovary removed 

 with almost no loss of blood. 



Bird no. 9030, operation 129. Bird not in laying condition. 

 Largest yolk about 8 mm. in diameter. Ovary in good healthy 

 condition : about two-thirds was removed. 



Bird no. 9026, operation 128. Bird in laying condition, 

 large yolks present; one-half of ovary removed. There was con- 

 siderable bleeding. 



Bird no. 9022, operation 127. Bird in nearly laying condition 

 but had stopped temporarily. Large yolks present; one-half 

 of ovary removed. There was considerable bleeding. 



Bird no. 9018, operation 125. Bird apparently healthy. 

 Ovary in very bad condition. Large number of absorbing yolks 

 and yolk tumors. Evidently septic condition, as all peritoneal 

 surface was thick and opaque. Removed large part of ovary 

 and all tumors. There was considerable bleeding. 



Bird no. 9023, operation 123. Bird in healthy condition. 

 Ovary not in laying condition; about two-thirds removed. 



Bird no. 9019, operation 126. Bird in healthy condition. 

 Ovary healthy, but in a non-laying condition. Less of ovary 

 removed than in either 127, 125, or 123. 



The pieces of removed ovary were placed in formalin and counts 

 later made. 



It was the original intention to keep these birds until they had 

 all started to lay, but this was found impossible, owing to lack 

 of time. As it was, half of the birds had started to lay, and it 

 was only a question of time before the others would begin, as 

 all the ovaries were in a very healthy condition. 



