§ 1. The effects following exposure of maturing unfertilized starfish eggs to high temperatures (29-36°) vary in a constant manner with the times of exposure as follows. Below a certain minimal duration of exposure to any given temperature (e. g., 32°), no visible change is produced in the egg; slightly longer exposures induce the formation of typical fertilization-membranes, but the eggs fail to cleave and soon break down without development; in order to induce favorable development an exposure of three to four times the minimum for membrane-formation is required (e.g., 7-8 minutes at 32°); more prolonged exposures are again followed by failure to develop. 2. Between 29° and 38° the times of exposure required to produce these effects decrease very rapidly with rise of temperature; on the average a rise of 1° approximately halves the exposure required for a given physiological effect (such as membrane-formation, or complete activation, or heat-inactivation). The activation-process thus exhibits a characteristically high temperature-coefficient (Q10 = 200-400). 3. The effects of exposure to weak butyric acid solution (n/260) vary with time of exposure in a similar manner,—brief exposure causing membrane-formation followed by breakdown, longer exposures causing cleavage and development to larval stages, and still longer exposures causing cytolysis without development. 4. The inference is that the same process is initiated in the egg by exposure to warm sea-water as by fatty acid solution. This process must proceed to a certain stage in order that activation may be complete; if arrested too soon (brief exposure) only partial activation (membrane-formation followed by breakdown) results. 5. Eggs in which membranes are formed by minimal exposure to warm sea-water or n/260 butyric acid, followed by return to sea-water, may be made to develop favorably by a second treatment with either warm sea-water or fatty acid solution, as well as by after-treatment with cyanide-containing or hypertonic sea-water. A favorable after-treatment may thus be of the same kind as the membrane-forming treatment. 6. The temperature-coefficient of activation by high temperatures is of the same order as that of the melting of gels or the decrease in the viscosity of gelatine solutions. The above high temperatures thus probably act by producing degelation-effects in the surface layer of the egg; increase of permeability, with consequent depolarization, is the result of this change. 7. A new hypothesis of the mode of action of hypertonic sea-water is put forward.
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Ralph S. Lillie (1915) studied this question.