108 JACQUES LOEB. 



ment had worn off. This was the case. The eggs no longer 

 disintegrated in sea-water. A fraction of these eggs was fer- 

 tilized later and segmented. 



When the eggs are transferred into normal sea-water imme- 

 diately after the butyric acid treatment they perish rapidly if 

 no second treatment is given to them. If they are treated with 

 hypertonic sea-water (50 c.c. sea-water + 8 c.c. 2 1/2 m NaCl 

 or NaCl + KC1 + CaCl 2 ) for from thirty to sixty minutes they 

 will develop into larvae. If they are treated longer they will 

 begin to develop but form very abnormal larvae. 



If the eggs, however, after the butyric acid treatment are not 

 put into sea-water but into a mixture of m/2 NaCl + KC1 

 + CaCl2 in which they form the thin membrane and if they 

 are kept here until they no longer disintegrate in normal sea- 

 water, they cannot be induced to develop when treated for from 

 thirty to sixty minutes with a hypertonic solution. Such eggs 

 have, therefore, in spite of their membrane formation gone back 

 into the condition of a resting egg. 



4. It was obvious from these experiments that the constit- 

 uents of the sea-water determine the nature of the membrane 

 after butyric acid treatment. The writer expected to find that 

 Ca was an absolute prerequisite for the membrane formation 

 but this was not the case, although the presence of CaCl 2 im- 

 proves the character of the membrane. Eggs that had been 

 taken out of a m/2 NaCl solution were treated with 50 c.c. m/2 

 NaCl + i c.c. N/io butyric acid for one and a half to two and a 

 half minutes. They were then transferred into the following 

 three sets of solutions: 



(i). NaCl + KC1, 

 (2). NaCl + CaCl 2 , 

 (3). NaCl + KC1 + CaClo, 



which were made in duplicates, the one set remaining neutral, 

 the second set faintly alkaline (0.5 c.c. N/ioo NaOH were added 

 to 100 c.c. of the solution). The result was not very different 

 in the neutral and alkaline solutions. Many but not all the 

 eggs put into NaCl + KC1 formed very thin membranes often 

 only in part of the egg. The membrane formation does there- 

 fore not require the addition of CaCl 2 , but the eggs transferred 



