172 INSECT PESTS 



by reason of its power to convert the various gases and 

 dissolved mineral matter into new cells within itseK and 

 not on the outside as we saw in the case of minerals. These 

 cells are a paradox to the mathematician, for they multi- 

 ply themselves by simple division ! The cell-wall con- 

 tracts and parts off the protoplasm into two portions, 

 each with a nucleus or life-centre, and the two halves, 

 instead of wandering about in search of each other, as 

 Plato said of human beings, straightway proceed to 

 become full-grown cells and perform a similar function in 

 their turn. In fact it does not matter which of them 

 considers itself the " better half," as the other one can 

 turn round and say " You're another " and still keep the 

 peace. But the process of cell division does not go on 

 indefinitely, the cells act as though they were buyers of 

 raw material and take from their central market, the 

 sap-stream and the atmosphere, just what each requires, 

 some to build new cells as described, and some to pack 

 their insides with corky or woody material so as to form 

 a hard stem, some to store up starch and sugar, and still 

 others are diverted to the business of flowering and repro- 

 duction. 



This last is the most interesting process of all, and 

 plants present an endless variety of method and device 

 in order to secure continuance of their land in the next 

 generation. 



The habit of the plant determines its leading character- 

 istics. For instance in the httle nursery poem which 

 runs : — 



' Down in a green and shady bed, a modest violet grew ; 

 Its stalk was bent, it hung its head, as if to hide from view. 

 And yet it was a wondrous flow'r, with petals soft and rare. 

 It might have graced a lovely bow'r, instead of hiding there. 

 Yet there it was, content to bloom, in modest tints array'd, 

 And there diffused a sweet perfume, within the silent shade. 

 Then let me to the valley go, this pretty flower to see, 

 That I may also learn to grow in sweet humility." 



