Human Physiology 



Fig. 2. 



ing the mineral matters required and selected; in the leaf, 

 this water is partly evaporated through its myriad pores, partly 

 decomposed, the oxygen given off, and the hydrogen combined 



with carbon, which is obtained from 

 the atmosphere, sucked in perhaps 

 through erectile stomata, some of 

 which draw in like the joints of a 

 telescope. By the aid of lighi water 

 and carbonic acid are both decom- 

 posed to make starch, oil, etc., and 

 the air is thereby freed of carbonic 

 acid and enriched with added oxygen. And in this wonderful 

 laboratory of the leaf are prepared the flavours of sweet and 

 sour apples, peaches, plums, grapes, strawberries, and all the 

 products o the vegetable kingdom, under the influence anvi 

 direction of the unknown power or principle of life. 



A proof that the leaves govern the functions 

 of plants, rather than the roots or stalk, is 

 shown by budding and grafting. A hundred 

 varieties of roses may be grown upon wild 

 briar bushes ; a hundred kinds of apples upon 

 crabs, and if you like to bud or graft so many, 

 a hundred kinds upon one tree. Each bud 

 has its own life, though all draw water from 

 the earth and live upon the same air. 



The pistil is the centre of most flowers, 

 consisting of the stigma at the top of the 

 style and at the bottom the germen, con- 

 taining the ovary. Figure 3 is a magnified 

 section of a pistil, showing the pollen grains 

 resting on the stigma, and communicating 

 through tubes thrown out for the purpose, with 

 the ovule, egg, or seed germ of the plant. 

 The modes of vegetable formation illustrate the powers of 



Fig. 3- 



