144 Artificial Parthenogenesis and Fertilization 



sea-water that contains benzol; but if HCl is added to this 

 sea-water, this membrane formation does not take place.^ 



If the eggs are transferred from the butyric acid solution, 

 not into sea-water, but into a neutral mixture of NaCl, KCl, and 

 CaCl2, often no proper membrane is formed. But if the eggs 

 are put into an alkaline mixture of NaCl, KCl, and CaCl2, 

 proper membranes are formed by the egg. 



The experiments, however, lead to still another unexpected 

 result. If the eggs are transferred from the acid solution into 

 the neutral mixture of NaCI, KCl, and CaCl2, they neither 

 develop nor disintegrate. They appear rather to return into 

 the resting condition in which they can be fertilized with sperm. 

 I have fertilized such eggs with sperm even after two days, 

 and could evoke development. 



The following experiment also shows that such eggs remain 

 in the resting condition if they are transferred from the acid 

 solution to the neutral mixture of NaCl, KCl, and CaCl2. 

 If the eggs are placed, after treatment with the fatty acid, in 

 sea-water or in an alkaline solution of NaCi, KCl, and CaCl2 

 (in which they form a perfect membrane), a further short treat- 

 ment with a neutral hypertonic solution is sufficient to cause 

 all the eggs to develop into larvae. In such an experiment it 

 was only necessary to leave the eggs from 20 to 50 minutes in 

 a neutral hypertonic solution (50 c.c. NaCl -f 2. 2 c.c. KCl-f- 

 1.5 c.c. CaCla, all m/2, -|-9 c.c. 2| m NaCl), to cause all the 

 eggs to develop into larvae. The eggs, however, which had 

 been transferred from the acid solution into the neutral solu- 

 tion of NaCl, KCl, and CaClj, could generally not be made to 

 develop even by 120 minutes' exposure to the neutral hyper- 

 tonic solution. This again shows that these eggs were really 

 in the resting condition. These facts are a new proof for the 

 statement made in a previous chapter, that the acid causes the 

 development of the egg only indirectly through the membrane 

 formation. 



1 Loeb, op. cit. 



