CORPUS LUTEUM IN OVARY OF THE CHICKEN 13 



A further test of its chemical nature was made by ti-ying 

 some of the various solvents used by Escher and by Palmer. 

 Sections were cut in paraffine and mounted on slides and then 

 the paraffine removed b}^ xylol and the sections treated with 

 different chemicals. This pigment is not the carotin described 

 by Palmer, but we could not reach any conclusion as to its 

 chemical nature, as nothing could be found to dissolve it. But 

 the fact of the identity of this pigment in the hen and cow is 

 proven beyond a doubt. Concentrated HCl, HNO3 and H2SO4 

 were tried and had no effect except that the H2SO4 turned the 

 particles dark brown and made them even more distinct than 

 before. For an alkali solvent, strong KOH was used; it turned 

 the pigment bright orange but did not ehssolve it. In adeUtion 

 to these various other solvents were tried after consultation with 

 the chemistry department, petroleum ether, sulphuric ether, ace- 

 tone, carbon bisulphide, and carbon tetrachloride, but none of 

 these had the slightest solvent effect on the pigment. Acetone 

 cleared the background and this made the particles stand out 

 more sharply. Carbon bilsulphide was allowed to act for sev- 

 eral hours, but the preparations still contained the pigment at 

 the enei of that time in undiminished degree. We conclude 

 that any two substances which can withstand the action of as 

 many well known solvents of as many different properties as 

 this list includes must be of very similar chemical nature. This 

 gives us one more proof that the yellow particles in the hen 

 ovary are the same as those in involuted mammalian corpora 

 lute a. 



VI. CHANGES IX ATRETIC FOLLICLES IN THE HEN'S OVARY 



Among the developing yolks and discharged follicles of the 

 hen ovary are many degenerating eggs. They can be distin- 

 guish d from developing eggs by the shrunken appearance as 

 though the contents did not ejuite fill out the foUicle. Eggs may 

 start to degenerate at different stages. Tbe largest one on the 

 Barred Plymouth Rock ovary was 12 mm. in diameter. Many 

 of them show dark spots which are masses of coagulated blood. 

 Mostly they are smaller than this when involution begins. The 



