THE WEB OF LIFE 281 



edible figs, and the female flowers, saved by long styles from 

 having eggs laid in them, are pollinated and produce normal 

 seeds. The female wasps go in and out till the swelling of 

 the juicy inflorescence nearly closes the opening. They 

 then migrate in autumn into small late inedible figs, where 

 they lay eggs. These eggs hatch into wingless males and 

 winged females, which remain inside the small figs through 

 the winter. The females escape in Spring before the dry 

 figs fall off, and then the story begins again. We must not 

 pursue the matter further : it is complicated by the exist- 

 ence of two cultivated varieties of the wild fig the inedible 

 caprificus with male flowers only, and the ordinary edible 

 domestica with female flowers only. Both are visited by 

 the Blastophaga wasp. 



OTHER RELATIONS BETWEEN PLANTS AND ANIMALS 



Many animals feed on plants ; many animals have their 

 home on or in plants (see Parasitism) ; many animals secure 

 the pollination of flowers and the distribution of seeds ; 

 a few animals hide themselves with a disguise of plants (see 

 Masking) ; a few animals have entered into an internal 

 partnership with plants ; but this list does not by any 

 means suffice to cover the extraordinary diversity of inter- 

 relations. Let us refer to a few of the many other kinds 

 of linkage. 



Alga on Sloth's Hair. A quaint association seems to 

 have become established between a unicellular Alga, like 

 the Pleurococcus which makes tree-stems green in wet 

 weather, and the shaggy hairs of the South American sloth 

 (Bradypus), which lives an altogether arboreal life. The 

 sloth has almost exactly the same greyish-green colour as 



