594 STUDIES IN GENERAL PHYSIOLOGY 



experiment which led me in the right direction. In this ex- 

 periment the following four mixtures were used: 



(1) 60 c.c. --f-n MgCl 2 +40 c.c. of sea-water 



(2) 60 c.c. YwKCl + 



(3) 60 c.c. YnNaCl + 



(4) 60 c.c. YwCaCla + 



A lot of unfertilized eggs were distributed in these four 

 solutions, and remained in the same for one hour and fifty 

 minutes. They were then brought back into normal sea- 

 water. The eggs that had been in the first (MgCl 2 ) solution 

 began to show an amoeboid change of form (indicative of a 

 segmentation) in about fifteen minutes after they were 

 brought back into normal sea- water. About one in a thousand 

 eggs were in this amoeboid stage. One does not see such 

 changes in the normal egg where the membrane limits the 

 amoeboid motions. Fifty minutes later one in a thousand 

 eggs divided into 2 or 3 cells. The cells were of about equal 

 size. About two and one-half hours after the eggs had been 

 put back into normal sea-water about one egg in five hundred 

 had segmented, and the segmentation had proceeded to the 

 eight-cell stage, although not all the eggs had reached this 

 stage. But then the development stopped. The next morn- 

 ing the eggs were still without any membrane. All looked 

 normal and healthy. In this experiment the volume of nor- 

 mal sea- water into which the eggs were put after they had 

 been in the MgCl 2 solution was small (only a watchglass full). 

 Hence the few drops of the MgCl 3 solution which were 

 transferred with the eggs modified the sea-water, and I 

 think interfered with their development. It seemed to me 

 that by avoiding this source of error, and by using large 

 dishes with several hundred cubic centimeters of sea-water 

 instead of the watchglass, it might perhaps be possible to 

 see the eggs develop fu-rther. 



The eggs that had been in solution 2 (60 c.c. KC1+40 



