46 M. R. CURTIS AND RAYMOND PEARL 



on them confirm and extend our previous conclusions in regard 

 to somatic and genetic sterility, and also in respect to the ability 

 of a bird to absorb rapidly through the peritoneum yolks dis- 

 charged into the body cavity. 



DATA 



Data on the nine cases of partial or complete sterihty are given 

 in table 1. From the figures in this table it is possible to com- 

 pare the performance record of each individual, both with the 

 anatomical condition of the sex organs at autopsy, and with 

 her genetic expectation, judged by the performance record of 

 her sisters. 



SOMATIC STERILITY 



Birds Nos. 141, 81, 364, and 383 belong to high producing 

 families. Not one of them had a sister which laid less than 

 thirty eggs before March 1 (Pearl '12). These birds themselves 

 would, therefore, be expected to be good layers. Examination 

 of the final columns of the table shows that Nos. 141, 81, and 

 364 could not lay for anatomical reasons. 



The oviduct of No. 141 had burst near the upper end of the 

 isthmus. In the body cavity was a yellow liquid composed 

 evidently of egg mixed with serum. In this liquid were many 

 short tubular pieces of egg membrane of approximately the 

 length of the portion of the isthmus anterior to the tear. The 

 opening in the wall was of such size that it was impossible for 

 an egg to pass it. The oviduct on both sides of the tear was in 

 normal laying condition. There was a normal egg (a yolk en- 

 closed in thick albumen) in the posterior end of the albumen 

 secreting region. In the ovary was a series of five normal yolks, 

 the largest apparently mature, and seven discharged follicles. 

 At the posterior end of the body cavity was an empty collapsed 

 egg membrane on which was a thin layer of shell. The perito- 

 neum was slightly thickened, so that it was translucent rather 

 than transparent. The viscera were normal. The bird was 

 evidently in perfect health. 



