STUDIES IN ARTIFICIAL PARTHENOGENESIS. IJI 



Inorganic Salts. That isotonic solutions of various salts 

 cause membrane "formation" was discovered by R. Lillie ('10). 

 The effectiveness of the various salts was found to correspond 

 with their order in the lyotropic series, i. e., those salts which 

 are most effective in producing swelling of protein gels (in 

 alkaline solution) were also most effective in inducing membrane 

 "formation." The reason for this correspondence becomes 

 apparent, when we consider that the membrane "formation" 

 produced by isotonic salt solutions is nothing other than a mem- 

 brane swelling. The membranes resulting from salt treatment 

 are sticky, they do not collapse in the presence of a colloid (cf. 

 p. i 60). 



The concentration of a salt is an important factor in deter- 

 mining whether swelling shall take place, and how pronounced 

 the swelling shall be. Let us consider as an example the case 

 of NaCl. Seven solutions of NaCl were prepared by adding 

 distilled water to a 2.5 normal solution. 



Thus Solution A contained 50 c.c. 2\ M NaCl plus o c.c. distilled water. 



B 40 10 



C 30 20 



D 20 30 



E 10 40 



F 5 45 



G 2\ 47-5 



Eggs were placed in all these solutions at 3:30 P.M. By 

 3:39 eggs in A showed a membrane swollen to 2.51* in diameter. 

 By 4:50 it had reached approximately $/j.. 



As for the eggs placed in B, the membrane swelled at least 

 as rapidly as in the first case. 



Membranes on eggs in C and D also swelled rapidly, but in 

 no case did eggs in E, F, G show any membrane swelling. Thus 

 a certain concentration is necessary for swelling to occur. 



There appears to be at least two factors involved in this effect 

 of concentration. In the first place, the swelling action of the 

 salt no doubt increases with the concentration. But it is prob- 

 able that the hypertonicity of the solution may also play a 

 role. 1 



1 The explanation of such an effect might be as follows : When water is extracted 

 from the cell, there is a tendency for vacuum production and consequent negative 

 pressure (release of pressure) on the particles of the membrane. But we know 



