INSECTS AND FLOWERS 209 



where the ovule would otherwise develop, 

 whilst at the same time they are not adapted to 

 the production of seeds capable of germination, 

 since no pollen-tubes can develop upon their 

 abortive stigmas. Evidently we have here a 

 case of complimentary functions or division of 

 labour in accordance with the following plan. 

 The wasps which deposit their eggs in the figs 

 carry the pollen both to the short-styled gall- 

 flowers and to the long-styled ordinary female 

 flowers, and attempt to lay their eggs in both 

 kinds of flowers. The gall-flowers are prepared 

 expressly for the reception of the wasps' eggs, 

 and young wasps actually develop in them, but 

 their stigmas not being adapted for the reception 

 of pollen, they do not promote the growth of 

 pollen-tubes, and no fertile seeds are produced. 

 On the other hand, pollen-tubes develop on the 

 stigmas of the long-styled flowers, and the latter 

 produce fertile seeds ; but the long-style pre- 

 vents the proper placing of the wasps' eggs, and 

 consequently galls are never or very seldom 

 produced in connection with these flowers. 



" It would take too long to discuss all the 

 numerous diversities which have been observed 

 in other species of Fig, even if they were known 

 with sufficient accuracy to admit of a general 

 survey. We will only mention that there are 

 approximately six'hundred species of Ficus, which 

 are distributed over the tropical and sub-tropical 

 regions of both the Old and the New Worlds, 

 and that up to the present time nearly fifty 

 species of small wasps of the genera Blastophaga, 

 Crossogaster, Sycophaga, and Tetrapus have been 



