108 TYPES OF BRITISH PLANTS 
All this sounds like a fairy tale, but the Yucca has 
been watched as it opened for the moth at dusk; the 
moth has been seen acting as I have described, and 
experiment after experiment has gone to show that the 
Yucea can produce no seed without the help of the 
moth. 
In the case of the Fig, the process is rather different. 
All the flowers grow closely crowded together, as it were, 
upon the inside of a flask, the neck being closed by a 
scaly arrangement, through which an insect can push its 
way. Near the top of the flask, or urn, the flowers 
consist of stamens only, but lower down there are flowers 
with pistils and no stamens, These pistils are of two 
kinds, one being much shorter in the shaft, or style, than 
the other. Within the short-styled ovary is a gall-wasp, 
which in time comes forth full-blown, and struggles over 
the stamen flowers to the mouth of the flask, covering 
itself with pollen in the effort. Then it crawls off to 
another flower, or rather, group of flowers, in order to 
lay eggs. Forcing its way into an adjoining flask, it 
passes down to the pistils and leaves some pollen upon 
those that are ripe, though not in this case, as with the 
Yucca moth, of set intention. It also proceeds upon its 
main business and lays its eggs promiscuously in short- 
styled and long-styled flowers alike. And here we find 
a most ingenious device. The long-styled flowers are 
protected from the gall-wasp, for it cannot set the egg 
deep enough to get at the ovary, and in the ovary new 
seed is safely produced; but the short-styled flowers suit 
it admirably, and a fresh generation is produced to 
fertilise other fig trees. On the other hand, it would be 
a waste of energy for these short-styled flowers to make 
seed which would be eaten up, for they are not necessary 
