28 CHANGE 



of the same flower head. Generally, however, 

 reproduction that results from the conjugation 

 of the sperm-cells and germ-cells of the same 

 flower or of the same plant is not as vigorous 

 as if these cells are derived from different plants, 

 and in many cases flowers are elaborately so con- 

 trived as to prevent self-fertilization and to leave 

 the germ-cells dependent upon sperm-cells (pollen) 

 which are brought from other flowers by insects, 

 or by the wind. But any general theory on this 

 question is marred by the fact that there are 

 tribes and very important tribes of plants 

 which habitually fertilize themselves, or are, even, 

 so shaped as to render cross-fertilization impos- 

 sible, so that the germ-cells are entirely dependent 

 upon the pollen of the flowers to which they 

 belong, and reproduction is effected by the 

 closest in-and-in breeding. This does not appear 

 to have lessened vitality : amongst these self- 

 fertilizing plants is the pea, which is exceedingly 

 vigorous in growth and in seeding. 



Amongst the simpler forms of animal life it may 

 also occur that the organs for the production 

 of sperm-cells and germ-cells are borne by the 

 same individual : this is even the case with earth 

 worms. But, as a rule, they are appropriated by 

 different individuals, and the distinction of sex comes 

 into being, together with the numerous correlative 

 developments of form, colour, and character that 

 mark the male off from the female. It is believed by 

 some biologists of the Mendelian school that a male 

 is, in essence, a female 1 plus a special character. 

 According to Mendel's law, the male would in this 



1 Amongst mammals the possession of teats by males appears to 

 indicate an underlying femininity. But it should be remarked that 

 from breeding experiments made with the Currant Moth (Abraxas 

 grossulariata) it would appear that it is the female, not the male, 

 which is the more complicated organism, and produces two sets of 

 reproductive cells that are distinct in their sexual potentiality. 



