8 



WASTE OF POLLEN. 



[CHAP 



birds. In the former case, however, by far the 

 greater part of the pollen is wasted ; and much more 

 must therefore be produced than in those cases where 

 the transference is effected by insects. 



One advantage, of course, is the great economy of 

 pollen. We have not much information on the sub- 

 ject, but it would seem, from the few observations 

 that have been made, that half a dozen pollen grains 

 are sufficient to fertilise a seed. But in plants in 



Fig. S. — Geranium fraiettse fefoung 

 flower). Five of the stamens are 

 erect. 



Fig. 6. — Geranium pratente (older 

 flower). The stamens have retired, 

 and the stigmas are expanded. 



which the pollen is carried by the wind, the chances 

 against any given grain reaching the pistil of another 

 flower are immense. Consequently by far the greater 

 part of the pollen is lost. Every one, for instance, 

 must have observed the clouds of pollen produced by 

 the Scotch fir. In such flowers as the Paeony the 

 pollen is carried by insects, and far less therefore is 

 required ; yet even here the quantity produced is still 

 large ; it has been estimated that each flower produces 



