Mechanism of Membrane Fokmation 



211 



water is raised by the addition of some NaOH (e.g., 1 . c.c. 

 N/10 to 50 c.c. sea-water), the chorion is gradually dissolved 

 in a number of eggs. The writer has recently found that the 



Fig. 63 



Fig. 64 



Fig. 65 



Figs. 63-65. — Dissolution of the chorion surrounding the egg of Lottia 

 gigantea, a mollusc, on treatment nith saponin. Fig. 63 shows the egg before the 

 treatment with saponin.* c is the chorion. Fig. 64 shows the same egg a few 

 minutes after the addition of saponin. The chorion c is greatly swollen and at 

 the point of liquefaction. Fig. 65 shows the chorion having completely disap- 

 peared and the egg become spherical. In this condition it is permeable for the 

 spermatozoon. 



weak bases are much more efficient than the strong bases. 

 Thus the amines and NH4OH will cause the swelUng and lique- 

 faction of the chorion of Lottia in the same concentration much 

 more rapidly than the strong bases NaOH and tetraethyl- 

 anomoniumhydroxide. 



