Mark. — Lepidosteus. 



ABBREVIATIONS. 



cap. Head of villus. 



c.-t. cp. Connective-tissue corpuscle. 



fits. mat. Maturation spindle. 



gran. Granulosa. 



m py. can. Micropylar canal. 



m py. cl. Micropylar cell. 



nl. Nucleus. 



nl. gran. Nucleus of granulosa cell. 



pd. Stalk of villus. 



rx. Root of villus. 



st. ml. Villous layer of egg membrane. 



th.ful. Membrana propria of theca f'olliculi. 



vac. Vacuole. 



vit. Vitellus. 



vs. g. Germinative vesicle. 



z. r. Zona radiata. 



PLATE IV. 



Fig. 1. Radial section through the micropyle and micropylar funnel, showing the 

 micropylar cell and a portion of the maturation spindle of an egg 

 "stripped" from the fish, preserved in 0.5 per cent chromic acid 

 (5 hours) followed by washing in water, and hardened in alcohol. 

 Stained in picrocarmine. X 515. 



" 2. The second section preceding that shown in Figure 1, and passing nearly 

 through the middle of the maturation spindle. X 515. 



" 3. View of the animal pole of an egg preserved in Merkel's fluid. The 

 germinal disk was rather more than half as broad as the diameter of 

 the egg, and its outline should have been represented more distinctly 

 by the lithographer ; it was of a yellowish color, but much lighter 

 than the rest of the egg. The micropylar funnel is seen exactly over 

 the centre of the disk. X about 10. 



" 4. View of the micropylar funnel and contained micropylar cell of the egg, 

 a section of which is shown in Figure 1. X 158. 



" 5. Radial section through the micropylar region and germinative vesicle of 

 an ovarian egg preserved in alcohol. A portion of the granulosa still 

 adheres to the outer surface of the villous layer. Stained in alcoholic 

 borax-carmine. X 158. 



