Katliarine Foot and E. C. Strobcll 241 



Photo. 74. x 710. Section of a vacuolated nucleolus of an oocyte from 

 the ovary. Fixative, corrosive acetic (20 per cent acetic) followed by osmic 

 acid. Unstained. 



PiiOTO. 75. X 710. Section of a nucleolus with dark granules. From an 

 oocyte in the ovary. Fixative, picro-acetic followed by osmic acid. Unstained. 



Photo. 76. X 710. Section of a small oocyte in the ovary showing the 

 nucleolus and yolk nucleus. Fixative, saturate corrosive sublimate followed 

 by osmic acid. Unstained. 



Photo. 77. x about 1100. Section of a nucleolus of an oocyte from the 

 ovary. Fixative, Flemming's fluid (strong). Stain, iron hsematoxylin fol- 

 lowed by dilute Bismarck brown. 



Photo. 78. x 710. Section of a young oocyte in the ovary showing a ring 

 nucleolus and archoplasm (yolk-nucleus) in the cytoplasm. Fixative, saturate 

 corrosive sublimate. Stain, iron hsematoxylin. 



Photo. 79. x 1000. Section of a ring nucleolus of an oocyte from the 

 ovary. Fixative, Merkel's fluid followed by osmic acid. Stain, iron hsema- 

 toxylin. (Photo. 8C was omitted by mistake.) 



PLATE V. 



All sections 2% ^ 



Photos. 81 and 82. x 1000. Two sections of a germinal vesicle of an 

 oocyte first order from the receptaculum ovorum. This vesicle was cut into 

 nineteen sections and the two reproduced here were fifteen sections apart and 

 both very close to the periphery of the germinal vesicle; the next section on 

 each side being the last to show the germinal vesicle. These photographs 

 show the earliest appearance of the centrioles and asters at opposite poles of 

 the germinal vesicle. The centriole in Photo. 81 is still in contact with the 

 membrane of the vesicle and the centriole in 82 is very close to the membrane. 

 Fixative, chromo-acetic. Stain, iron hfematoxylin followed by dilute Bismarck 

 brown. 



Photo. 83. x 1000. Section of a germinal vesicle of an oocyte first order 

 from the receptaculum ovorum. The centriole and aster are further developed 

 than those in Photos. 81 and 82 and not so close to the membrane of. the 

 germinal vesicle. The other centriole is eleven sections from the one in this 

 photograph. Fixative, Boveri's picro-acetic. Stain, iron hsematoxylin fol- 

 lowed by dilute Bismarck brown. 



Photos. 84 to 89. x 1000. Consecutive sections of a germinal vesicle of 

 an oocyte first order from a receptaculum ovorum. 86 and 87 are photographs 

 of the same section, 86 being taken on the plane of the small centriole, and 87 

 on a lower plane to show the rest of the chromosomes. The two centrioles are 

 seen at opposite poles in Photos. 84 and 86. There are two accessory nucleoli 

 in Photo. 89. Traces of the persisting membrane of the germinal vesicle are 

 seen in nearly all the sections. Fixative, Rabl's picro-sublimate. Stain, iron 

 hsematoxylin followed by dilute Bismarck brown. 



Photos. 90 and 91. x 1000. Two planes of the same section of a first 

 maturation spindle in an oocyte from a receptaculum ovorum, showing four of 

 the eleven chromosomes. Both centrioles are in this section but not on the 

 same plane as the two chromosomes of Photo. 90. One centriole is shown in 

 Photo. 91, which was taken before staining and focused for the unstained 



