DISPERSION OF POLLEN BY ANIMALS. 161 



longer in their galls and are there fertilized by the males. Afterwards they come 

 out also (c/. fig. 240^^), but only stay a short time within the cavity of the inflores- 

 cence, issuing from it as soon as possible into the open air. They accordingly crawl 

 up to the mouth of the inflorescence, and in doing so they come into contact with 

 the pollen of the male flowers and get dusted all over the body — head, thorax, 

 abdomen, legs, and wings. After squeezing through between the scaly leaves at 

 the mouth of the inflorescence, and having at last reached the outside, they let their 

 wings dry and then run ofl' to other inflorescences on the same or on a neighbouring 

 Fig-tree. I say "run" advisedly, for they but rarely make any use of their wings 

 in this act of locomotion. They now seek exclusively inflorescences which are in 

 an earlier stage of development, that they may lay their eggs in the ovaries. 

 Having found such an one they crawl to the opening and slip between the scales 

 into the interior. Sometimes their wings are injured in the act of entering, indeed, 

 the wings are occasionally broken off altogether, and are left sticking between the 

 scales near the aperture. 



Once inside the inflorescence, the wasps immediately devote themselves to laying 

 eggs, and in the process are of necessity brought into contact with the stigmas of 

 female flowers. The wasps are still powdered over with the pollen from their 

 birthplace, and it is now brushed ofl" on to the stigmas, which are thus pollinated 

 from another inflorescence. If the pollen is deposited on normal pistilliferous 

 flowers the latter are able to develop seeds endowed with the power of germination; 

 if it falls on gall-flowers it is, as a rule, ineffectual, because the stigmas are more or 

 less abortive. Moreover, no seeds are formed in these gall-flowers, owing to the 

 eggs of the wasp being laid in their place. In those species of Fig in which gall- 

 flowers are not specially provided, the eggs are laid in a certain proportion of the 

 normally-developed female flowers. It has, however, been observed in the case of 

 the Common Fig (Ficus Garica) that eggs of Blastophaga grossorum laid in 

 ordinary female flowers do not come to maturity, or, in other words, that a normal 

 female flower is not converted into a gall, even if the wasp in question sinks its 

 ovipositor into it and deposits an egg in the interior. For the style of the normal 

 female flower of Ficus Carica (fig. 240") is so long relatively to the ovipositor of 

 Blastophaga grossorum that the egg cannot be inserted quite into the ovary, but is 

 left at a spot which is not favourable to its further development and there perishes. 

 The gall-flowers of this species of Fig, with their short styles (fig. 240"), are, on 

 the other hand, pre-eminently adapted to the reception of the egg at the spot 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 complementary 

 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 flower. The gall-flowers are prepared expressly for the 

 reception of the wasps' eggs, and young wasps actually develop in them ; but their 



Vol. II. 61 



