170 INSECT PESTS 



water) drawn up out of the soil. The plant can, from 

 the mere appropriation of these substances, grow from a 

 small and simple seed to a great and complex community 

 of specialized cell structures. How is it done ? Is a 

 plant (or an animal) the only thing that grows ? What 

 about a snowball which rolls down the hill and commenc- 

 ing at about the size of a dumpHng, becomes large enough 

 to floor a bullock ! Or suppose we visited one of those 

 curious places called " dropping wells " and placed an 

 old flat-iron or other object therein, returning in course 

 of time to find it not only apparently changed to stone, 

 but actually grown in size. Or take as a more ready 

 instance the beautiful " ferns " drawn on the window- 

 pane by Jack Frost in a single winter's night, growing in 

 that short space of time with marvellous variety and 

 profusion. 



Are these cases at all comparable to the growth of a 

 plant ? Clearly not, for there is one striking difference, 

 viz. that whereas all mineral substances, snowballs, 

 crystals, sedimentary deposits or what-not, " grow " by 

 additions of the same substance on the outside; 

 plants (with animals) take into their " winding stair-case " 

 on the inside aU manner of difiPerent substances and 

 convert them into ceU material. This at once indicates 

 the gulf that divides life from inert mineral matter, for 

 the crystals and the lime deposits were merely accretions, 

 whilst the plant or the animal performs a miracle which 

 we cannot explain, and we call it the miracle of growth. 



We said that plants must breathe by means of lungs. 

 Well, look at the enlarged plan and section of a portion 

 of the bean leaf. The numbers of little mouths or pores 

 (called stomata) take in air during bright sunshine and 

 it passes into the Uttle chambers marked (c) which occur 

 all through the plant structure, where carbon is extracted 

 and oxygen given o£F, exactly the opposite of the breath- 

 ing process in animals, so that the leaves are in every 

 sense of the word lungs. They also act collectively as a 



