3^4 O.V THE NUMBER OF POLAR BODIES AND [VI. 



division, as is the rule in the eggs of most animals, or by the 

 division and removal of part of the egg-nucleus alone. The 

 occurrence of the latter method of elimination certainly con- 

 stitutes a still further proof of the physiological importance 

 of the process, and this, taken together writh the universal 

 occurrence of polar bodies in all eggs — parthenogenetic and 

 sexual — forces us to conclude that the process must possess a 

 definite significance. No one of the various attempts which 

 have been made to explain the significance of polar bodies 

 generally is applicable to the first polar body except that which 

 I have attempted. 



But the case is different with the significance of the second 

 nuclear division, or the second polar body. Here it might 

 perhaps be possible to return to the view brought forward by 

 Minot, Balfour, and van Beneden, and to consider the removal 

 of this part of the nucleus as the expulsion of the male part 

 of the previously hermaphrodite egg-cell. The second polar 

 body is only expelled when the egg is to be fertilized, and at 

 first sight it appears to be quite obvious that such a preparation 

 of the egg for fertilization must depend upon its reduction to 

 the female state. I believe however that this is not the case, 

 and am of opinion that the process has an entirely different 

 and much deeper meaning. 



How can we gain any conception of this supposed herma- 

 phroditism of the egg-cell, and its subsequent attainment of 

 the female state ? What are the essential characteristics of 

 the male and female states ? We know of female and male 

 individuals, among both animals and plants : their difterences 

 consist essentially^ in the fact that they produce different kinds 

 of reproductive cells ; in part they are of a secondary nature, 

 being adaptations of the organism to the functions of repro- 

 duction ; they are intended to attract the other sex, or to ensure 

 the meeting of the two kinds of reproductive cells, or to enable 

 the fertilized egg to develope and sometimes to guide the 

 development of the offspring until it has reached a certain 

 period of growth. But all these differences, however great 

 they may sometimes be, do not alter the essential nature of the 

 organism. The blood corpuscles of man and woman are the 

 same, and so are the cells of their nerves and muscles ; and 

 even the sexual cells, so different in size, appearance, and 



