BIOLOGICAL STUDIES OF FIGS. 917 



parent until the egg of the Blastophaga is laid. In the 

 edible fig no gall flowers have been found with certainty, 

 at least the Blastophaga wasp, for whose special benefit 

 these gall flowers seem to have originated, has never been 

 found breeding in the edible figs. It has been supposed 

 that the cause of this was to be sought in the sugary juices 

 of the edible fig, which killed the eggs or embryo of the 

 wasps, but I am satisfied that this is not exactly true. 

 Many varieties of wild fig species produce very sweet 

 fruits, edible and quite palatable, and still these figs serve 

 as home for Blastophagas. The cause for the inability 

 of the wasp to breed in common figs must be sought for 

 elsewhere, and, as I will presently point out, is due to the 

 fact that the edible figs contain flowers modified to such 

 an extent that they are unsuitable as breeding places for 

 the wasps. 



The gall flowers are characterized by a much shorter 

 style, by an undeveloped stigma, devoid of receptive 

 glands, and by an imperfect embryo which never devel- 

 ops more than to a certain limited degree. The discov- 

 ery of the distinction between gall flowers and female 

 flowers is due to Solms-Laubach (25). 



Until his researches were made known it was supposed 

 that the female flowers turned into galls when stung by 

 the wasps. He again proved that the distinction existed 

 independent of the wasps, which however only select 

 the peculiar gall flowers as the only ones suitable to re- 

 ceive their eggs. 



Mule Flowers. — Under this name I arrange the major- 

 ity of the flowers of that class of edible figs, varieties 

 which mature their figs regularly without the presence of 

 the caprifig and its pollen. These flowers are, as far as 

 I know, not found in the caprifig, nor in any other wild 

 fig species. They are undoubtedly a product of culture 



