PLANT LIFE ON THE FARM. 



become the seed, and which is usually overtopped by a 

 little thread, called the " style," whose upper end, again, 

 is dilated into a " stigma." In the case of the wheat and 

 other grasses these stigmas are covered with fine white 

 silky hairs. The essential constituents of the flower, 

 without which reproduction cannot be effected, are the 

 pollen grains and the ovule. All other parts of the flower 

 are mere accessories, and some of them are very frequently 

 absent without the process of reproduction being impaired 

 by their absence. 



The process of fertilisation may be described in general 

 terms as follows : The ovule contains, in a cell just beneath 

 the skin at its summit, one special piece of protoplasm, 

 the " germ," which is destined to develop into the embryo 

 plant. The pollen-cell consists of an outer coat and an 

 inner lining ; the outer coat bursts, and the inner proto- 

 plasmic lining is protruded in the form of a tube, \vhich 

 passes down between the cells of the stigma and style, 

 growing in length and feeding as it goes, like a parasitic 

 fungus, on the contents of the cells of the style, till it 

 reaches the ovule and comes into close proximity to, if not 

 actually into contact with, the germ. In consequence of this 

 action a cell-wall is formed around the germ, which latter 

 divides and subdivides in various directions, the result 

 of the subdivision being the formation of an embryo plant, 

 as mentioned at p. 76, while the ovule covering the embryo 

 ripens into the seed. The germ is thus fertilised by the 

 pollen or sperm-cell, and unless the two come in contact, 

 the formation of the embryo plant does not take place. 



Cross Fertilisation. It has been mentioned that the 

 flowers with which the farmer is concerned have for the 



