24 HOW PLANTS EMPLOY INSECTS TO WOEK FOR THEAI, 



brought against the sticky stigma, -which occupies all the lower face of the shelf, 

 and at the next instant raises the lid to receive another charge of pollen. 



46. Before proceeding further to consider how particular flowers are arranged 

 to be helped by some particular sort or class of insects, and each in some pecu- 

 liar way, we should contemplate the remarkable conclusion to which we are 

 brought. It seems to be this : — these flowers are so constructed that the pol- 

 len, however near the stigma, is somehow prevented from reaching it of itself, and 

 then honey and other allurements are provided to tempt insects to come and convey 

 the pollen to the stigma. And the various contrivances for hindering the pollen 

 from reaching the stigma directly are excelled only by those for having it done in 

 a roundabout way. So Nature appears to place obstacles in the way, and then to 



- overcome the difficulty of her own making by calling in the aid of insects ! This 

 is blocking the wheels with one hand and lifting the vehicle over the obstruction 

 with the other. Or it is as if the wagoner of the fable, who prays Hercules to 

 help him out of the mire, had bogged his team merely for the sake of calling upon 

 Hercules. This is simply insredible. The explanation of one puzzle has brought 

 in its train a greater puzzle still. 



47. The solution of this puzzle is simple enough when once hit upon, althoiigh 

 it has taken a long time to find it out. It not only makes everything plain as 

 respects all these flowers, but also, as a true discovery should, clears up and 

 explains a great many things besides. The explanation is, that 



48. Cross-Fertilization is aimed at. The pollen was not intended to fertilize that 

 same flower, but to be conveyed to some other flower of the same species. So in- 

 sects, which had seemed to be needful only when the stamens and pistils are in 

 separate flowers, or on separate plants, are quite as needful, — indeed, are more 

 needful — where these organs stand side by side in the same blossom. The rea- 

 son why crossing is advantageous, and in the long run necessary, is that 



49. Breeding-in-and-in is injurious. Close-fertilization, that is, the fertilization of 

 the seeds by pollen from the same flower, is very close breeding indeed. It is 

 the next thing to no fertilization at all in plants, that is, to propagation by buds, 



■ — which may go on, as we know, for a long time : but it is not probable that any 

 species could always continue in that way. Cultivators and stock-breeders are 

 obliged to close-breed to keep a particailar race of few individuals true and to 

 heighten its desirable qualities. But sooner or later (in animals soon), more or 

 less wide breeding is necessary to keep up vigor and fertility. Wide-breeding is 



