MULTIPLICATION. 87 



but they gradually assume a very different appearance in the 

 course of their development to fit them for their work of aid- 

 ing fertilisation. It is not necessary in this place to enter 

 into details as to the floral construction, which varies indiffer- 

 ent plants ; the important points in relation to our present 

 subject are the stamens and the pistils and their contents. 



Within the green scales which constitute the flower of 

 wheat, within the butterfly- shaped and brightly-coloured 

 petals of the pea or the clovers, and the yellow petals of the 

 flowers of the turnip or the colza, the rape or the mustard, 

 are a series of fine thread-like bodies, the "stamens," varying 

 in number, size, and arrangement in different flowers, but 

 each consisting of a fine thread or stalk, called the 

 " filament." Surmounting this is a sort of pocket or 

 case, called the " anther," containing a yellow or greenish 

 dust, which, when examined with a lens, is seen to be made 

 up of separate cells or grains, called the pollen grains. Some 

 idea of the number of these pollen grains may be gained 

 from the calculations of Mr. A. S. Wilson, who estimates, 

 from the actual counting of a portion, that each anther 

 of rye contains 20,000 pollen cells, 500,000 of which are 

 needed to make up one grain in weight. A floret of spring 

 wheat in like manner was found to contain 6864 grains, 

 but, as the pollen grains of the wheat are larger than those 

 of the rye, only 390,000 are required to make up a grain 

 weight. An acre of wheat may, it is further calculated, 

 produce 50 Ib. of pollen, and an acre of rye 2 cwt.* 



Within the stamens, in most flowers with which farmers 

 have to do, is a "pistil," consisting of a thick portion 

 below, which contains the young "ovule" destined to 



* A.. S. "Wilson, in Gardeners Chronicle, March 21, 1874, p. 376. 



