MULTIPLICATION. 81 



thorough ripening, but that exposure to light is also 

 requisite, a dull, cloudy summer, even if warm, being 

 unpropitious to ripening, whether of fruit or grain. 



CHAPTER VI. 

 MULTIPLICATION. 



Sub-division. Intermarriage. Buds, Branches, Tillering, Tubers. 

 Fertilization, Stamens, Anthers, Pollen, Pistil. Mechanism of Fer- 

 tilization. Cross-Fertilization. Transport of Pollen. Insect 

 agency. Self-Fertilization. Fertilization of cereals. Hybridiza- 

 tion. Germination. 



Multiplication. There are two special ways in which 

 plants multiply. One is a mere process of extension or 

 subdivision a modified form of growth, in fact. The 

 other is the result of the union or commingling of a por- 

 tion of the protoplasm of one plant with a corresponding 

 particle of another plant. In the lower plants, as they 

 are designated, it is not even necessary that union of 

 particles of protoplasm from different plants should be 

 effected. The contents of one cell blend with the con- 

 tents of another cell on the same plant, and the result is 

 the formation of a seed or spore, by means of which the 

 plant is reproduced. The first process of multiplication, 

 by division, is called asexual, the second sexual, because 

 it is a process of intermarriage requiring the co-operation 

 of two distinct particles of protoplasm. In the very 

 lowest plants these two particles present no appreciable 

 differences, but in the higher plants and animals they 

 present such differences as to enable us to distinguish 

 one as male, the other as female. In the lowest plant 

 the two particles are split off from the same mass of pro- 

 toplasm, while in the higher plants the male element is 

 formed from a different source from the female. 



