FERTILIZATION-REACTION IN ECHINARACHNIUS PARMA. 



The cytolysis theory is based on results obtained with over- 

 exposed eggs. Loeb argues that because a toxic agent like 

 saponin, benzole, toluene, etc. destroys the egg, its normal de- 

 velopment or its artificial parthenogenesis is likewise a destructive 

 (cytolytic) process solely because in many cases the toxic agent 

 if allowed to act but a short time induces membrane formation ; 

 prolonged exposure being cytolytic, the shorter exposure which 

 induces membrane formation must therefore be cytolytic. It 

 would be tedious to cite the pages in which this argument appears. 

 A single quotation will suffice. " We can therefore say briefly 

 that all hemolytic agencies effect the activation of the unfer- 

 tilized egg and this activation consists in a cytolysis of the cor^- 

 tical layer of the eggs." The italics are Loeb's. 



Moreover, Loeb practically tells us, as pointed out above that 

 with Arbacia he employed over-exposed eggs and also that he used 

 as a criterion for activation the rapidity with which the death 

 changes (cytolysis) set in after treatment. The proper exposure 

 for Arbacia eggs as first determined by Heilbrunn is much shorter 

 than that which Loeb used and gives beautiful full membranes 

 instead of the jelly-like film of the over-exposed egg. This over- 

 exposure, therefore, simulates neither the cortical changes in- 

 duced by the " complex ' living spermatozoon ' ' nor the artificial 

 membrane formed through properly timed exposure. 



The cytolysis theory, in the next place, is based on the super- 

 ficial resemblance of cytolyzing eggs to cleaving eggs. Loeb 

 continually speaks of " cleavage " when he means disintegration. 

 Thus, page 76, he figures the " slow disintegration of the egg of 

 the sea urchin at low temperature " which " can reach the eight 

 cell stage." Butyric acid does not call forth cleavage in these 

 urchin eggs. Herlant records much the same experience. Loeb 

 also states that "centrosomes and two astrospheres are formed 

 and the nucleus divides." Again, in the experience of others (cf . 

 Herlant, also Just) the egg treated with butyric acid alone does 

 not go beyond the monaster stage. 



Likewise, on purely logical grounds the cytolysis theory should 

 be rejected. Influenced in large measure no doubt by the interest 

 then prevailing in the field of hemolysis, Loeb sought to bring 

 the explanation of his work on " artificial parthenogenesis " in 



