FERTILIZATION 75 



were, self-fertilized. Many egg cells which thus de- 

 velop without fertilization do not lose half their chromo- 

 somes, and thus the cells of the resulting individual 

 carry the full number, notwithstanding the lack of any 

 contribution from a sperm. 



5. Still more surprising, however, is the fact that Artificial 

 Dr. Jacques Loeb has been able in a number of cases to gen esis, 

 bring about artificial parthenogenesis. This means that cause . d b y 



J . . chemical or 



he has succeeded in causing development in unfertilized physical 

 eggs through the action of various chemicals, or even by stimuli 

 mechanical or physical stimuli. In all such cases, of 

 course, there is no possibility of the union of protoplasm 

 from different individuals. It begins to appear, then, 

 that if we mean by fertilization that which induces 

 growth, the protoplasmic union has little to do with it. 



6. Dr. Loeb also found that development may often Deveiop- 



, , , i .1 r ment caused 



be made to occur by introducing the sperm ot some bythe 

 quite different animal ; for example, sperm of a sea s P erm of 

 urchin added to eggs of a starfish. The resulting or- animals 

 ganisms would develop properly, but would show only 

 maternal characters. That is, they would possess none 

 of the characters of the male parent, the sperm of which 

 had "fertilized" them. Evidently, then, even here 

 there had been no intimate protoplasmic union. 



7. The final conclusion is, that the egg cell contains Cross- 

 within itself all the essential factors for development. 



Since, however, bisexual reproduction has come to be cells with 

 the normal method among the higher animals and pow ers 

 plants, typical egg cells develop qualities which cause 

 them to remain latent until a sperm arrives. It is like 

 the sleeping beauty in the old story, waiting to be 

 awakened by the right prince. In parthenogenesis she 

 awakes of her own accord, or in response to some un- 

 toward disturbance. In a sense, there is less of magic 



