IO2 HARRY B. YOCOM. 



birds in which the females are more brilliantly colored than the 

 males. Such a sex difference is characteristic of the Phalarope. 

 During the spring migration when the birds are in full breeding 

 plumage the females are easily distinguished from the males by 

 the more brilliant plumage of the back and neck. Bailey (1917) 

 states the sex differences as follows : ' Male in breeding plumage ; 

 upper parts dark plumbeous, striped on back with buff and black: 

 sides of neck rufous, chest gray, upper throat and belly white. 

 Female in breeding plumage; brighter colored, rufous extending 

 across throat as well as on sides of neck. " To one not acquainted 

 with the facts concerning the sex differences of this group of 

 birds the sexes would undoubtedly be mistaken. During the 

 fall migration both males and females are lighter in color due to 

 the loss of the rufous color and more nearly resemble one another. 



In one respect the sex differences of the Phalarope do not com- 

 pare with the sex differences of the fowls and that is in the fact 

 that the color differences in the Phalarope are not associated 

 with structural differences in the feathers, as is usually the case 

 In the fowls. A microscopical examination of the feathers of the 

 Phalarope showed that the color was due to pigment and not to a 

 difference in structure. Whether or not this is an important 

 difference and alters our problem can be determined only by a 

 study of a large number of birds or different races. 



The material w r ith which this study has to deal consists of the 

 gonads of both male and female Northern Phalarope, Phalaropus 

 lobatus, Linn., collected during both fall and spring migrations 

 along the Oregon coast. The tissues were taken from the birds 

 as soon as possible after they had been shot, and were put into 

 Bouin's fluid and left until it was convenient to care for them in 

 the laboratory. Delafield's li.rmatoxylin was found satis- 

 factory and was used almost exclusively as a stain. 



A studs' of the testes gave only negative results. In no case 

 were there found any groups of cells resembling the characteristic 

 packets of luteal cells found in the testes of the Sebright, and not 

 even single cells which might be considered of that type. The 

 intertubular material was not abundant and consisted of narrow 

 spindle shaped cells with oval, more or less shrunken nuclei. 



In the ovary, however, characteristic groups of the so-called 

 luteal cells were found in the theca surrounding the oocyte follicles 



