3i6 THE ASCENT OF MAN 



the female. Though a primitive method of Re- 

 production, the process in this case foreshadows the 

 law of all higher vegetable life. From this point 

 upwards, though there are many cases where Re- 

 production is asexual, in nearly every family of 

 plants a Reproduction by spores takes place, and 

 where it does not take place its absence is abnor- 

 mal, and to be accounted for by degeneration. 

 When we reach the higher plants the differences 

 of sex become as marked as among the higher 

 animals. Male and female flowers grow upon sepa- 

 rate trees, or live side by side on the same branch, 

 yet so unlike one another in form and colour that 

 the untrained eye would never know them to be 

 relatives. Even when male and female are grown 

 on the same flower-stalk and enclosed in a common 

 perianth, the hermaphroditism is generally but 

 apparent, owing to the physiological barriers of 

 heteromorphism and dichogamy. Sex-separation, 

 indeed, is not only distinct among flowering plants, 

 but is kept up by a variety of complicated de- 

 vices, and a return to hermaphroditism is pre- 

 vented by the most elaborate precautions. 



When we turn to the animal kingdom again, the 

 same great contrast arrests us. Half a century 

 ago, when Balbiani described the male and female 

 elements in microscopic infusorians, his facts were 



