IO4 HARRY H. YOCO.M. 



luteal cells were numerous. In many sections there would be no 

 packets at all while in others there would be one or two. In all 

 cases where found the packets were clearly defined and easily 

 demonstrable, being composed of cells having a relatively large 

 amount of cytoplasm with rounded nuclei. The cytoplasm of the 

 luteal cells takes very little of the haematoxylin stain. In this 

 respect as well as in shape and size these cells differ from the cells 

 of the stroma of the ovary. 



The facts cited above do not indicate that luteal cells are in 

 any way influential in suppressing color development in the 

 Phalarope. In their consideration of the influence of the luteal 

 cells on feathering in fowls Boring and Morgan have not separated 

 the factors for color and structure in the feathers. In the present 

 study only the color of the feathers is considered. The fact that 

 luteal cells are found in the ovary while the female is so much more 

 brilliantly colored seems to eliminate the possibility that the 

 secretions of the luteal cells in any way suppress color develop- 

 ment. 



The evidence so far obtained is not sufficient to warrant any 

 statement in regard to the problem of the association of color 

 differences with structural differences in the feathers. 



The recent work of Nonidez (1922) raises another question 

 the solution of which will in a large measure depend on a more 

 extensive study of the presence or absence of luteal cells in the 

 gonads of birds. This author has shown that the so-called luteal 

 cells as designated by Pearl and Boring and Boring and Morgan 

 are in reality only the degenerating sex cords of the embryonic 

 gonad. What have been termed luteal cells and what have been 

 understood to be homologous with the corpus luteum of mammals, 

 Nonidez has shown to have an entirely different origin and are 

 therefore not to be confused in terminology with the mamma- 

 lian tissues. Whether or not these remains of the sex cords may 

 have an endocrine function is left l>y the author as an open 

 question to be determined by a wider study of a variety of mate- 

 rial. The facts as presented above as regards the presence of 

 these cells in the gonads of the Phalarope do not seem to bring us 

 any nearer a solution of the problem. There is no indication, 

 in the Phalarope, that these groups of cells exert a suppressing 

 influence on the development of the color of the feathers of the 



