MORACEAE 139 



The mutual adaptation of plant and insect to each other, 

 which the remarkable mode of pollination in Ficus reveals, 

 is one of the most interesting chapters of Natural History. 



The insects visiting the figs at their flowering season 

 are little wasps of the tribe Chalcidiae, and as far as 

 known, each species of Ficus is inhabited by its own 

 particular kind or kinds, that of the cultivated fig being 

 named Blastophaga grossorum* . 



There are three kinds of florets, their distribution 

 differing according to species. In Ficus capensis each 

 inflorescence appears to contain all three kinds, but in 

 other species purely female receptacles also occur. The 

 female insect having found its way through the ostiole 

 into the young fig, deposits its eggs in the ovaries of the 

 gall flowers, which are short-styled, while the long style 

 of the perfect florets does not allow the ovipositor to 

 enter the ovary. The inflorescences are distinctly proto- 

 gynous, and the male flowers at this stage still undeveloped. 

 When, however, the larvae are full grown and begin to 

 change into the adult, winged insect, the male flowers 

 develop and their anthers open, exposing the pollen. 

 As these flowers are situated around the ostiole, the 

 insects, in endeavouring to escape, become dusted with 

 pollen, and when at last successful they carry some of 

 it to the next young fig, which is in its first stage, thus 

 effecting cross -pollination. 



It is specially noteworthy, that the plants are not 

 only dependent upon the insects for the transport of the 

 pollen, as is the case in many other flowers, but that here 

 the anthers of the male florets do not even properly 

 develop unless the gall flowers have become infested with 

 the insect, the stimulus produced by the development of 

 the latter being evidently transmitted to the former. 



* The insects of the South African species of Ficus belong to several genera, but for 

 the sake of convenience one may retain the general designation Blastophaga (see page 136). 



' 18—2 



