ON THE NUMBER OF POLAR BODIES 



AND THEIR SIGNIFICANCE 



IN HEREDITY. 



PREFACE. 



The following paper stands in close relation to a series of 

 short essays which I have published from time to time since 

 the year 1881. The first of these treated of 'The Duration of 

 Life,' and the last of 'The Significance of Sexual Reproduction.' 

 The present essay is most intimately connected with that upon 

 ' The Continuity of the Germ-plasm,' and has, in fact, grown 

 out of the explanation of the meaning of polar bodies in the 

 animal egg, brought forward in that essay. The explanation 

 rested upon a trustworthy and solid foundation, as I am now 

 able to maintain with even greater confidence than at that 

 time. It rested upon the idea that in the egg-cell, a cell with 

 a high degree of histological differentiation, two different kinds 

 of nuclear substance exert their influence, one after the other. 

 But continued investigation has shown me that the explanation 

 built upon this idea is only correct in part, and that it does not 

 exhaust the full meaning of the formation of polar bodies. In 

 the present essay I hope to complete the explanation by the 

 addition of essential elements, and I trust that, at the same 

 time, I shall succeed in throwing new light upon the mysterious 

 problems of sexual reproduction and parthenogenesis. 



It is obvious that this essay can only contain an attempt at 

 an explanation, an hj^pothesis, and not a solution which is 

 above criticism, like the results of mathematical calculation. 

 But no biological theory of the present day can escape a similar 

 fate, for the mathematical key which opens the door leading to 



