. Senescence and rejuvenescence. Age; Reproduction. THE GAMETES IN PLANTS AND ANIMALS 339 egg of the cycad Zamia; Fig. 175, the archegonium of a conifer, Torreya iaxifolia, containing the large egg: incidentally this figure also shows the pollen tube with the two small male nuclei near the tip. The development of the female gamete in the angiosperms is outlined in Figs. 141, A-E (p. 321). Fig. 176 is the embryo sac of the sun- flower at the time of ferti- lization, and Fig. 177, that of the coneflower, another composite, at the same stage. The eggs in all these plants are manifestly highly spe
. Senescence and rejuvenescence. Age; Reproduction. THE GAMETES IN PLANTS AND ANIMALS 339 egg of the cycad Zamia; Fig. 175, the archegonium of a conifer, Torreya iaxifolia, containing the large egg: incidentally this figure also shows the pollen tube with the two small male nuclei near the tip. The development of the female gamete in the angiosperms is outlined in Figs. 141, A-E (p. 321). Fig. 176 is the embryo sac of the sun- flower at the time of ferti- lization, and Fig. 177, that of the coneflower, another composite, at the same stage. The eggs in all these plants are manifestly highly specialized cells which have undergone great changes from the embryonic condition. The animal egg usually exhibits an even greater de- gree of morphological specialization than that of the plant because it is loaded to a greater or less degree with granules or masses of yolk substance which becomes available as a nutritive supply at the beginning of embry- onic development. The accumulation of yolk is often so great that the egg cell attains an enormous size, the bird's egg representing the extreme of development in this direction. Since the period of growth and differentiation of. Figs. 168-172.—Peculiar forms of sperma- tozoa from the arthropods: Figs. i68, 169, 170, Pinnotheres, Maja, and Munidia, all Crustacea (from Koltzoff, '06a); Figs. 171, 172, Acanto- lophus, Agalena, both spiders (from Bosenberg, 'OS).. 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 Child, Charles Manning, 1869-1954. Chicago, Ill. , The University of Chicago Press
Size: 1096px × 2279px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectreproduction, bookyea
