ARTIFICIAL PARTHENOGENESIS 583 



from its low degree of dissociation becomes intelligible if we 

 asume that the NH4OH which diffuses into the egg influences 

 the rate of oxidations more strongly than the alkali which acts 

 merely on the surface of the egg. On this assumption the 

 external surface of the egg is neither the only nor perhaps the 

 main seat of oxidation, but oxidations occur also in the inter- 

 ior of the egg. 



Another fact which would agree with such a view is the fol- 

 lowing: The egg of the Californian sea urchin, Strongylocen- 

 trotus purpuratus, cannot develop in an acid or in a neutral solu- 

 tion. It suffices, however, to add a small amount of neutral 

 red to the salt solution to start the development. Neutral 

 red is a much weaker base than NH4OH and diffuses rapidly 

 into the egg. It is not well conceivable that neutral red could 

 accelerate the oxidations in the sea urchin egg except on the 

 assumption that NaOH acts only or at least mainly on the sur- 

 face, while neutral red acts in addition inside the egg. Since 

 in this case the action of the alkali consists also in an accelera- 

 tion of the rate of the oxidations this would also point towards 

 the probability that the external surface is not the only seat 

 of oxidations in the cell. 



Finally, it should not be overlooked that the strong bases 

 NaOH or KOH have also a small parthenogenetic effect. In 

 view of the experiments mentioned in this paper this fact sug- 

 gests the possibili-ty that the strong bases diffuse into the egg 

 to a slight extent, or at least into its cortical layer. It is proba- 

 ble that for this diffusion only the undissociated molecules of 

 these bases are to be considered. The fact that the strong 

 bases do not change the color of the neutral red contained in 

 the egg does not contradict such an assumption, if we suppose 

 that the base acts in the egg through salt formation with an 

 acid constituent of the egg, e.g., an acid protein. 



6. Membrane formation by alkali 



In his former experiments on the parthenogenetic action of 

 alkalies in Strongylocentrotus the writer pointed out that the 



