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. 25 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 EGcs WHIcH DEVELOPED INTO LARVAE AFTER 
REMAINING IN THE SOLUTION 
Beeine |o45! \.20" (| 25% | 30": lgS5! of 40 | 45 50" 
eee eo 0 |..01 01” af 30| 90,| 98°! 100 
Fe | 0 | 0 4/ 40| 70| 90} 98 $04 real ee 
ieee a0 che [10] 30.) 70 90 | 100 a ie 
! 
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. 
