. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. THEORIES OF FERTILIZATION 269 it is blood, in the case of the frog, or hypertonic sea water, as used by Loeb in the sea-urchin egg, introduces a catalyzer which converts the monaster into an amphiaster, and in this way renders the egg capable of cleavage. Bataillon placed great emphasis upon the exudation (excretion) of sub- stances into the perivitelline space and the elevation of the fertilization mem- brane. He believed that the unfertilized eg
. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. THEORIES OF FERTILIZATION 269 it is blood, in the case of the frog, or hypertonic sea water, as used by Loeb in the sea-urchin egg, introduces a catalyzer which converts the monaster into an amphiaster, and in this way renders the egg capable of cleavage. Bataillon placed great emphasis upon the exudation (excretion) of sub- stances into the perivitelline space and the elevation of the fertilization mem- brane. He believed that the unfertilized egg was inhibited because of an accumulation of metabolic products and that activation or fertilization led to a release of these substances to the egg's exterior. For discussion, consult Wilson, '25, p. 484; J. Brachet, '50, p. 144. Lillie, F. R., '14, '19. This author postulated that a substance, fertilizin, carried in the cortex of the egg, exerts two kinds of actions in the activation process: (1) An activating, attracting, and agglutinating action on the sperm, and (2) an activating effect on the egg itself. In essence, the egg is self- fertilizing, for the fertilizing substance is present in the egg. The procedure is somewhat as follows: At the period optimum for fertilization, inactive fertilizin (, inactive from the viewpoint of possessing the ability to activate the egg) is produced by the egg. Released into the surrounding water, it activates, attracts, and agglutinates the sperm at the egg's surface. As the sperm touches the egg, it unites with a part of the fertilizin molecule. The ENTRANCE OF SPERMJ FIRST MATURATION DIVISION- SECOND MATURATION DIVISION —. FIRST MATURATION DIVISION — ENTRANCE OF SPERM SECOND MATURATION DIVISION—'. 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 Nelsen, Ol
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