984 CALIFORNIA ACADEMY OF SCIENCES 



enter the fig except they knew the Blastophagas were al- 

 ready there. The most important point, however, is the 

 quantity of insects required at a given time. Only an 

 insect which will actually breed in the caprifig can be de- 

 pended on, and it must breed in countless numbers. A 

 few visitors would have no practical influence on the fig 

 crops. They may fertilize or pollinate a few flowers, 

 but they would be of no practical value to the grower and 

 would not produce a crop. Taking it all in all no insect 

 has been known, and no one is likely to ever be known 

 that can be substituted for the Blastophag-a -psenes. 



Different Species of Blasto-phaga in Different Figs. — 

 As far as is known, different species of figs are, as a rule, 

 inhabited by distinct and characteristic species of inqui- 

 lines. Thus one, Biastophaga -psenes, has only been found 

 in one or two nearly related fig species, and no other 

 Blastophaga species has been found in our caprifigs. 

 Parasitical wasps are always found together with the 

 Blastophag£e, preying on and developing in them, just as 

 the Blastophaga preys on and develops in the embryo of 

 the fig. Even when different fig species grow close 

 together, do the wasps keep to their respective fig hosts; 

 accidentally the wasps may visit other figs, but they do 

 not breed in them. It appears as almost certain that every 

 fig species is inhabited by Blastophag£e. Thus, in the 

 botanical garden of Java (88) a row of fig trees, consist- 

 ing of five different species of figs, was found to be 

 inhabited by as many different species of Blastophaga, 

 each variety in its own fig host, to which it was strictly 

 confined (90). The cause of this localization of species 

 must be sought in the organization of the wasps and 

 their ovipository organs, which only enables the insect 

 to deposit its eggs in a certain kind of flower, which 

 again has been changed so as to accommodate the pecu- 



