io6 



JACQUES LOEB. 



the eggs form a membrane which is very thin and which is at 

 first at a great distance from the egg. Figs, i and 2 give an idea 

 of the first appearance of this membrane; the membrane in 

 Fig. i was formed in a neutral, that of Fig. 2 in a faintly alkaline 

 solution. Later on, the membrane collapses and is found lying 

 rather close to the egg. Such eggs can be readily fertilized with 

 sperm in spite of the existence of the membrane. The latter 

 is either naturally permeable for sperm or it is easily torn and 

 thus allows the sperm to reach the egg or it is not entirely con- 

 tinuous around the eggs. 



FIG. i. 



FIG. 2. 



Eggs were washed three times in a mixture of m/2 NaCl + 

 CaCl 2 + KC1 and then put for from one and a half to two 

 and a half minutes into 50 c.c. m/2 NaCl + KC1 + CaCl 2 + i.o 

 c.c. N/io butyric acid. From this solution they were transferred : 



(a) Into normal sea-water. 1 



(6) Into a neutral mixture of m/2 NaCl + KC1 + CaCl 2 . 



Lot a formed normal fertilization membranes and disinte- 

 grated in a few hours. The eggs of lot b formed the fine fertili- 

 zation membrane which was at first very distant from the egg. 

 Some of these eggs were transferred into normal sea-water after 

 one hour. These eggs did not form a better membrane but per- 

 ished in the same way as the eggs of lot a. 



A second portion of lot b was transferred into normal sea- 

 water after having been for seven hours in the mixture of m/2 



1 Such eggs have at first a tendency to stick to the glass when transferred to 

 sea-water. It is necessary to keep them in slight agitation for some time until they 

 have lost their tendency to stick. 



