Mars. — Lepidosteus. 



ABBREVIATIONS. 



cap. Head of villus. pd. Stalk of villus. 



c.-t. cp. Connective-tissue corpuscle. rx. Root of villus. 



fus. mat. Maturation spindle. st. vil. Villous layer of egg membrane. 



gran. Granulosa. th.fol. Membrana propria of theca folliculi. 



m py. can. Mieropylar canal. vac. Vacuity. 



m py. cl. Mieropylar cell. vit. Vitellus. 



nl. Nucleus. vs. g. Germinative vesicle. 



nl. gran. Nucleus of granulosa cell. z. r. Zona radiata. 



PLATE VIII. 



Figures 1 and 2 are from sections of an ovarian egg about 0.4 mm. in diameter 

 which was hardened in chromic acid. X 510. 



Fig. 1. Part of the peripheral portion of a radial section in which the earliest ob- 

 served trace of the villous layer has made its appearance. The 

 membrana propria of the theca and the follicular epithelium are arti- 

 ficially separated from the yolk and villous projections. 



" 2. Tangential section from the same egg. The section embraces connective- 

 tissue cells of the stroma, as well as follicular epithelium, and lias also 

 cut off a portion of the periphery of the yolk, with its villous pro- 

 jections, which last give it a dotted appearance. The nuclei of the 

 epithelium are often lobed. vac. indicates vacuities evidently due 

 to depressions in the surface of the yolk, not to vacuoles in its 

 substance. 



" 3. Portion of a section which, owing to the wrinkled condition of the surface 

 of the egg, affords a surface view of the granulosa, as well as a radial 

 section and surface view of the villous layer. Some of the detached 

 villi are seen at one side. The nuclei of the granulosa cells still have 

 irregular lobed forms. Chromic acid preparation of an egg about 

 0.6 mm. in diameter. X 510. 



" 4. View of the villi as seen from the surface of an egg after it has lain for 

 some time in water. X 472. 



" 5. Amber-colored bodies found at the outer surface of the villous layer of 

 the egg membrane. X 472. 



