ON THE CAPACITY FOR FERTILIZATION AFTER THE INITIATION OF DEVELOPMENT

Abstract

1. If Arbacia eggs are exposed to a weaker and a stronger concentration of sea-water for varying lengths of time a perceptible gradient of effectiveness from the entire absence of any reaction to an essentially normal parthenogenetic reaction is apparent. 2. The effective exposure is accompanied by a perceptible condition of increased permeability and substances escape from the eggs. 3. The superposition of insemination on the optimum hypertonic treatment does not increase the percentage of development. 4. Eggs when exposed to hypertonic sea-water for two hours usually cannot be fertilized; and in such a condition fertilizin cannot be detected by any known method. If however there yet remains a certain capacity for fertilization, fertilizin can be detected by its sperm agglutinating properties. 5. If Arbacia eggs are exposed to activating agents the permeability of the egg is increased, substances are lost from it and fertilization is impossible. 6. If eggs are sectioned, after insemination subsequent to an exposure to the weaker Hypertonie solution, a gradient of activity of spermatozoa parallels, to a certain extent, the length of the exposure to hypertonic sea-water. 7. If eggs are sectioned after insemination, subsequent to an exposure to the stronger hypertonic solution, large numbers of eggs are seen to have several spermatozoa within their boundaries; but they usually do not exhibit any signs of activity; many are undergoing degeneration. 8. Sperm, in gaining extrance to an egg, are pulled out into a long thin chromatin band situated in the protoplasmic cone produced by the protoplasm of the egg. 9. If a pure culture of the first two cells, produced by cleavage, are inseminated, sperm enter, remain entirely quiescent, and may even undergo disintegration. They do not fertilize the blastomeres. 10. These experiments furnish no evidence for, but are contrary to, any view that a spermatozoön carries a substance into the egg that is necessary for development. There is no evidence of a sperm-borne "lysin-like" substance nor a secondary "corrective agent." The egg possesses all the essentials for development.