. Text-book of embryology. Embryology. FOWL—LATER DEVELOPMENT 555 Up to about the eleventh day the contraction's of the amnion remain very active, but thereafter they gradually become more gentle until during the closing days of incubation they stop. The mesonephros also attains to its maximum activity and there commences the process of degeneration which will continue till the time of hatching: tubules have developed throughout the length of the metanephros. By the twelfth day the duct of the pituitary body has become reduced to a solid cellular strand: the exact time at which this happens is
. Text-book of embryology. Embryology. FOWL—LATER DEVELOPMENT 555 Up to about the eleventh day the contraction's of the amnion remain very active, but thereafter they gradually become more gentle until during the closing days of incubation they stop. The mesonephros also attains to its maximum activity and there commences the process of degeneration which will continue till the time of hatching: tubules have developed throughout the length of the metanephros. By the twelfth day the duct of the pituitary body has become reduced to a solid cellular strand: the exact time at which this happens is very variable; it may be as early as the sixth or seventh day. The lachrymal duct, which originated as a solid ingrowth of ectoderm along the line of the lachrymal groove, now becomes tubular. About the twelfth or thirteenth day the cavity reappears over the greater part of the rectum except just at the hinder limit of the occluded portion immediately in front of the allantois. Here the cavity remains blocked till nearly the time of hatching. olf. .. v /" % -1 H .. rnx-'~i^Ufm I X^jjj i V n. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original MacBride, E. W. (Ernest William), 1866-1940; Kerr, John Graham, 1869-; Heape, Walter, 1855-1929. London : Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, bookpubli, booksubjectembryology
