. Chemical embryology. Embryology. SECT. 2] AND WEIGHT 493 pigeon (i8 days), the guinea-fowl (25 days), the duck (26 days), the partridge (27 days), and the turkey (28 days). The results were related to weights of embryos equal to those of the chick embryo on different days, and as can be seen, the values for the other embryos fell uniformly on the chick curve. The length of incubation would thus appear to be a tune played as it were, " adagio " in the turkey and "allegro" in the pigeon.* o EI D m H6N : ^Ko^ Partridse: Hen : \NKUre Wyo>«Ulte Pigeon DUCK Turkey gui
. Chemical embryology. Embryology. SECT. 2] AND WEIGHT 493 pigeon (i8 days), the guinea-fowl (25 days), the duck (26 days), the partridge (27 days), and the turkey (28 days). The results were related to weights of embryos equal to those of the chick embryo on different days, and as can be seen, the values for the other embryos fell uniformly on the chick curve. The length of incubation would thus appear to be a tune played as it were, " adagio " in the turkey and "allegro" in the pigeon.* o EI D m H6N : ^Ko^ Partridse: Hen : \NKUre Wyo>«Ulte Pigeon DUCK Turkey guinea-fowu Hen • Ba/»*»««ei<Ur. % of total incubation time Fig. 74- The possible adaptive significance of incubation time has been shown remarkably in a paper by Friedmann, who found that the incubation times of the cowbirds, such as Agelaioides, Molothrus and Tangavius, varied according to their degree of parasitism. M. afer, which is very parasitic, has an incubation time of 10 days (the * For this it was necessary to assume that the pre-natal growth-curves for wet weight were alike, an assumption which was subsequently shown to be legitimate by Kaufmann. The instantaneous percentage growth-rates of the pigeon and the hen do not begin to differ until after hatching; and this holds, according to her, for heart, liver and eye, as well as for the whole body. The cells of the pigeon embryo, however, are smaller than those of the chick by about 30%.. 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 Needham, Joseph, 1900-. New York: The MacMillan Co.
Size: 1733px × 1442px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublishernewyorkthem, booksubjectembryology
