XIII 



THE RELATIVE PHYSIOLOGICAL EFFICIENCY OF 

 VARIOUS ISOSMOTIC SOLUTIONS 1 



As already mentioned, I had in 1900 published the obser- 

 vation that the development of the egg of Arbada can be 

 initiated by a pure sugar solution. 2 These experiments had 

 already shown that the pure sugar solution exerted a stronger 

 osmotic effect than it should theoretically. 



The following experiments were performed upon the eggs of 

 S. purpuratus in which membrane formation had been previ- 

 ously produced by treating them with butyric acid. The 

 eggs were placed in the hypertonic solution some ten minutes 

 after membrane formation, and hence the time of exposure 

 is longer than it would be had they been transferred to the 

 hypertonic solution half an hour after membrane formation. 

 We will start with experiments with pure sodium chloride 

 solution. 



The experiments with pure hypertonic solutions of NaCi 

 gave results that are, at first glance, paradoxical; for the eggs 

 after membrane formation can tolerate a higher concentration 

 of NaCl solution than of hypertonic sea-water. We shall see, 

 however, that this paradox finds a simple explanation. The 

 unfertilized eggs of a female were made to form membranes by 

 treating them with butyric acid, and then (about ten minutes 

 later) they were divided among 50 c.c. J m NaCl +3, 4, 5, 6, 

 7, 8, 10, 12, 14, and 16 c.c. 2^ m NaCl; some of the eggs were 

 transferred to normal sea-water after 55, 90, and 120 

 minutes. The temperature was 13 C. 



1 Loeb, "Ueber den Unterschied zwischen isosmotischen und isotonischen 

 Losungen bei der kiinstlichen Parthenogenese," Biochem. Zeitschr., XI, 144, 1908. 



2 Loeb, Am. Jour. Physiol, IV, 178, 1900. 



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