Archive image from page 54 of The development of the chick. The development of the chick : an introduction to embryology . developmentofchi02lill Year: 1936 DEVELOPMENT PRIOR TO LAYING 37 The entrance of several spermatozoa appears to be character- istic of vertebrates with large ova; thus for instance, it has been described in selachii, some amphibia, reptiles, and birds. Such a condition is known as polyspermy; it is normal in the forms mentioned, but occurs only under abnormal conditions in the Kc--''va.';.\...-. -J . fete â¢.:,â pfe::.,:: .;::. 3g:',-'. â ..â .;â¢â¢; â¢â â¢â â¢â¢;.'
Archive image from page 54 of The development of the chick. The development of the chick : an introduction to embryology . developmentofchi02lill Year: 1936 DEVELOPMENT PRIOR TO LAYING 37 The entrance of several spermatozoa appears to be character- istic of vertebrates with large ova; thus for instance, it has been described in selachii, some amphibia, reptiles, and birds. Such a condition is known as polyspermy; it is normal in the forms mentioned, but occurs only under abnormal conditions in the Kc--''va.';.\...-. -J . fete â¢.:,â pfe::.,:: .;::. 3g:',-'. â ..â .;â¢â¢; â¢â â¢â â¢â¢;.'â ⢠'?K-'i.''-''-.'.'.vi--'-v'-'.':'. â '.â â â¢â .'â¢â â -â â â¢.: - ⢠â¢'''','}y»;i'''-'-V'''' .â .â¢â .â .â¢â H»;;.;;-; JV â .â 'v-f;';.-;-'-:rJi Y~' _ Fig. 14. â Horizontal section of the germinal disc of a pig- eon's ovum immediately after ovulation, x 125. (After Harper.) N., Nucleus, probably first maturation spindle, p. r., Polar ring. Sp. N., Sperm nuclei. m. .V''-:-'':'--4-'>?va >f--;':- â .â¢â â¢â .,â¢'. â â¢.â¢â -,..â .â -. â¢â â ;--.:-''ftdsT| ;..v â¢â ;â â â â â¢'â¢â â¢â¢xâ¢;:â¢:-:â >i::V'ivâ¢:ii Fig. 15. â Vertical section of the pigeon's egg showing germ nuclei (pronuclei) in the center of the disc, x 2000. (After Harper.)
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