ACTION OF THE HYPERTONIC SOLUTION 



97 



treating them for two minutes with 50 c.c. of sea-water +2 . 9 c.c. 

 N/10 butyric acid (which was thoroughly mixed). One portion 

 of the eggs (A) was placed at once in hypertonic sea-water 

 (50 c.c. of sea-water +8 c.c. 2f m NaCl), a second portion (B) 

 thirty minutes later, and a third portion (C) after two hours. 

 At intervals of five minutes a portion of the eggs was replaced 

 in normal sea-water, the number of eggs undergoing segmenta- 

 tion ascertained, and, on the following day, the number of 

 larvae that had been produced was counted. Table VI gives 

 the result. The upper horizontal line shows how long (in 

 minutes) the eggs remained in the hypertonic solution and 

 underneath is shown the percentage of the eggs in each part 

 that grew into larvae. 



TABLE VI 



PERCENTAGE OF THE EGGS WHICH DEVELOPED INTO LARVAE AFTER 



REMAINING IN THE SOLUTION 



The temperature of the hypertonic solution was 15 C. 



What is the cause of this variation in time required for the 

 exposure to the hypertonic solution? I suspect that it has 

 something to do with changes which occur in the egg after the 

 membrane formation. One of these changes is the formation 

 of a fine gelatinous layer around the cytoplasm, which does not 

 begin until at least ten or fifteen minutes after the membrane 

 formation. It may be that the hypertonic solution only or 

 mainly takes effect after a definite change has taken place in 

 the egg. 



In all the experiments hereafter mentioned, the eggs were 

 transferred some ten minutes after membrane formation ; hence 

 the length of exposure is somewhat as in series A. 



