FIG. 269 
] 
LAN TY 
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Figs. 269-283. — Development of Teleost, Serranus atrarius, (After H.V. WILSON.) 
Fig. 276 X 25. 269. Egg immediately prior to segmentation, showing position of germ 
disc and of oil globule. 270, Germ disc after first cleavage. 271. Germ disc after third 
cleavage. 272. Vertical section of blastula, 273: Vertical section of blastula, sh 
origin of periblast. 274. View of marginal cells of blastula of similar stage. 275. G 
of blastoderm around yolk mass. 276. A slightly later stage, showing growth of embryo, 
277. Continued growth of embryo and reduction in size of the blastopore. 278. Sagittal _ 
section of tail region of embryo of last figure. 279, 280, 281. Cross-sections of embryos, __ 
showing successive stages in the development of notochord, gut, neuron, mesoblast. 282, 
Cross-section of young embryo, showing the mode of formation of gill slit, 283. Embryo 
shortly before hatching. 
A. Anus. AU. Auditory vesicle. BP. Dorsal lip of blastopore. CH. Notochord, 
EC. Ectoderm. ZN. Entoderm, G. Gut. GD. Germ disc. G&. Germ ring, GS, 
Gill slit. H. Heart. HP, Head process. AV. Kupffer's vesicle. MM. Spinal nervous 
system. MZS. Mesoblast. MP. Marginal periblast cells, OG. Oil globule. OL. Ol- — 
factory pit. OP. vgs capsule, /. Periblast. PS. Primitive ents, SC. ‘ 
tation cavity, SCH, Subnotochordal rod. 7M. Tail mass. Y. Yolk. . 
208 
