I90 Regeneration 



taken place — such as that caused by the entrance of 

 a spermatozoon into the egg — no reversal is possible; 

 although the development of the fertilized egg may be 

 suppressed for a long time by either low temperature 

 or lack of oxygen, or, in the case of seeds and spores, by 

 lack of water. But as soon as the conditions for the 

 chemical reactions in the egg are normal again, the 

 development may go on unless the egg has suffered by 

 the methods used to prevent development or by the 

 long duration of the suppression. With an incomplete 

 destruction of the cortical layer both development as 

 well as reversal of development are possible. Thus the 

 writer has shown that in the egg of Arbacia the effect 

 of the cortical alteration of the egg induced by the 

 butyric acid treatment or by the treatment with bases 

 can be reversed. When unfertilized eggs of Arbacia are 

 put for from two to five minutes into 50 c.c. sea water + 

 2.0 c.c. N/io butyric acid they will all form a gelatinous, 

 somewhat atypical fertilization membrane; when put 

 back into normal sea water all will perish in a few hours 

 unless they are submitted to the short treatment with a 

 hypertonic solution mentioned in the previous chapter, 

 while if submitted to this treatment they will develop. 

 If, however, these eggs are transferred from the butyric 

 acid sea water not into normal sea water but into sea 

 water containing some NaCN (10 drops of A per cent. 

 NaCN or KCN in 50 c.c. sea water), and if they remain 

 here for some time {e. g. overnight) they will not perish 



