302 RALPH S. LILLIE. 



be favorable to — since it will supplement — the action of any- 

 dehydrating mechanism; and it is possible that in the sea- 

 urchin egg after membrane-formation the intracellular dehydra- 

 tion-processes are by themselves not quite energetic enough to 

 effect the syntheses necessary for initiating development, but 

 become so when supplemented by the action of the hypertonic 

 sea-water; i. e., this agent has the effect of reducing the con- 

 centration of water at the locus of the reactions sufficiently to 

 enable syntheses to take place which otherwise are impossible 

 under the conditions. It is significant that cell-division is 

 started in the sea-urchin egg by simple membrane-formation, 

 but fails to continue, — just as if there were some failure in the 

 supply of the necessary constructive materials; partial abstrac- 

 tion of water rectifies this condition. Since oxygen is necessary 

 to this corrective process, we may assume that the syntheses 

 belong in part to the class designated by Schmiedeberg^ as 

 oxidative syntheses. 



From this general point of view the action of hypertonic 

 sea-water becomes in a measure theoretically intelligible and 

 ceases to be merely a detached empirical fact. Certain avenues 

 of experimental approach to the problem are also suggested. 



Summary. 



§ I. 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-mem- 



(as compared with about 5 per cent, under normal conditions) ; in more concentrated 

 solutions there was a decline. They also found that too long exposure to a favorable 

 solution (10 per cent.) was unfavorable; thus yeast incubated in 10 per cent, dextrose 

 for 2I hours showed an increase in glycogen-content from 4.84 per cent, to 11.66 

 per cent.; four hours later there was a decline to 9.33 per cent. These facts show a 

 suggestive parallel with the effects of hypertonic sea- water on sea-urchin eggs; 

 here also there is no effect until a certain minimal osmotic pressure is reached; 

 with further increase in osmotic pressure there is a rapid increase in favorability 

 up to an optimum; still further increase is unfavorable. Also for a favorable con- 

 centration there is at any temperature a definite optimum time of exposure. 



^ Cf. Schmiedeberg, Archiv f. exper. Pathologic u. Pharmakologie, 1893, Vol. 31, 

 p. 281. 



