218 PLANT LIFE 



vegetative activity. Loeb and others have 

 shown this to be experimentally possible 

 with eggs of various animals ; and although it 

 has not yet been satisfactorily demonstrated 

 in plants, this is largely owing to the very 

 small size of the egg, and to its ordinary 

 inaccessibility for purposes of this kind of 

 experiment. There is no doubt that the 

 essential processes are identical in animals 

 and plants, and, moreover, we are aware of 

 instances amongst the latter in which eggs 

 can be stimulated, though by indirect means, 

 to grow and develop in the absence of 

 fertilisation. 



We do not as yet at all understand and 

 yet this lies very near to the root of the whole 

 matter why the sexual change should pro- 

 duce two kinds of states. We speak of these 

 states as male and female respectively in the 

 higher forms, but there is no detectable 

 difference between the gametes of the sim- 

 plest organisms. Why there should be this 

 difference of state, and why the coalescence 

 of two individuals should not only obliterate 

 it, but give special vigour to the resulting cell 

 we are not as yet in a position to declare. 



As we pass from the lower to the higher 

 ranks of the vegetable kingdom, we find 

 that the primary physiological differences by 

 which sex is first differentiated are betrayed 

 by secondary changes which enable the male 

 to be distinguished from the female gamete. 

 The general trend of the distinction is un- 



