LECTURE I 



THE ORIGIN OF SEX IN PLANTS 



DIFFERENCES of Sex, and the fact that the sexes mate 

 and breed, are obvious for the Higher Animals, and for 

 Man himself. Hence the fact of Sex in Animals was 

 recognised from the earliest times. This is shown by the 

 Mosaic Cosmogeny, which reflects the knowledge of still 

 earlier periods. There is, however, no such early reference 

 to Sex in Plants. It is true Aristotle and Theophrastus 

 explained certain facts relating to the Fig and the Date 

 on a theory of Sex, based on an assumed analogy with 

 what was then known of the Higher Animals. But this 

 was no more than vague surmise. Real knowledge of 

 the facts of Sex in Plants was still wanting, however 

 clearly it might be realised that propagation was effected 

 by means of the Flower, and the Seeds produced from it 

 in the Higher Plants. 



Neither in Animals nor in Plants could any detailed 

 knowledge of Sex be expected till after the invention of 

 the compound microscope, for the sexual cells themselves 

 are minute. The compound microscope came into use 

 at the end of the seventeenth century. But it was long 

 after that before the details of sexual propagation in 

 Plants were actually observed. The story has been 



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