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DESCRIPTION OF PLATES XI AND XII. 



Illustrating Mr. Calderwood's paper on " A Contribution to our 

 Knowledge of tlie Ovary and lutra-ovarian Egg in Teleos- 



teans. 



PLATE XI. 



Fig. 1. — Formiug lamella of common dab, showing the ova separated into darkly 

 stained and light zones, and the subsequent splitting of the light zone from the dark. 

 Young ova developing from epithelial cells are seen filling up the remaining spaces of the 

 lamella. Zeiss D, oc. 2. 



Fig. 2. — Transverse section of ovary of common dab becoming ripe, showing the three 

 sizes of ova, the great having no nuclear membrane, and the rapidly thinning ovarian wall. 

 Zeiss CC, oc. 2. 



Fig. 3. — Highly magnified nucleus of eg§ taken from same section as Fig. 2, showing 

 absence of nuclear membrane and budding nucleoli. Zeiss F cor., oc. 4. 



Fig. 4. — Portion of section from spent ovary of common dab, showing the three sizes of 

 ova, large egg still with nucleoli although zona radiata disappeared ; also portion of egg in 

 advanced state of disintegration. 



Fig. 5. — Transverse section of intra-ovarian ovum of conger becoming ripe. Nucleoli 

 with circular arrangement of granules. 



PLATE XII. 



Fig. 6, a, h, c. — Three successive stages in the development of nucleus in ripening 

 conger, a. Nuclear membrane distinct ; nucleoli arranged regularly, numerous, showing 

 clear bands across short axis. h. Showing ultimate development of clear bands into 

 vesicles, which are expelled from the nucleoli, and merge with the yolk-spherules, c. 

 Nuclear membrane gone ; protoplasm encroaching on former space of nucleus ; nucleoli 

 few j vesicles still forming ; nucleolar matter seen outside area. Zeiss F cor., oc. 2. 



Fig. 7. — Vacuoled small ova without nucleoli dividing, taken from margin of longi- 

 tudinal section of spent ovary of common dab. Zeiss F cor., oc. 2. 



Fig. 8. — From same section as Fig. 7. Ovum from centre of spent ovary of common 

 dab. Nucleoli present ; ovum showing signs of division. Zeiss F cor., oc. 2. 



Fig. 9. — A longitudinal section of lamella of ovary from common dab in process of being 

 built up after spawning. It is a later condition than that seen in Fig. 4. The germinal 

 epithelium is rapidly forming minute ova, and the follicular layer of the larger eggs is also 

 appearing. The small masses of epithelial cells also forming minute ova are seen in various 

 stages of development at n. 



Fig. 10. — Section showing the egg-membranes in the almost ripe ovum of the sole. 

 S = follicular layer, z = zona radiata. x = the inner membrane described by KupfEer 

 as the vitelline membrane. 



Fig. 11. — Inner surface of fibrous envelope of spent ovary, showing the first appearance 

 of the connective-tissue cells. Zeiss F cor., oc. 2. 



Fig. 12. — Later stage in the development of connective-tissue cells on the inner surface 

 of ovarian envelope, showing a collection of the cells into a mass previous to their separa- 

 tion from the fibrous portion of the wall. Zeiss D, oc. 2. 



