156 THE MICROSCOPE AND ITS LESSONS. 



Potatoes contain 75 per cent, of water; turnips and 

 carrots, 80 per cent. A sunflower plant consumes twenty- 

 two ounces of water daily. Three million pounds weight 

 of water, it has been said, would be required for an acre 

 of sunflowers; five millions for an acre of cabbages; 

 six or seven millions for one of hops. Through the 

 agency of this vital fluid plants take up all the elements 

 of their composition, and much is absorbed from the 

 earth through the roots. Now you will understand why 

 last summer (1890) we have had such a wonderful 

 growth, if you remember the gracious showers which 

 have fallen. 



Experiments made with the grain and straw of oats 

 have given the extraordinary result of eleven different 

 descriptions of inorganic matter assimilated into the life 

 of the plant from the soil and the air, weighing (in 1000 

 Ibs.) nearly 26 Ibs. in the grain, and 57^ Ibs. in the straw ; 

 and this wonderful combination of eleven inorganic sub- 

 stances includes potash, soda, lime, magnesia, alumina, 

 oxide of iron, oxide of manganese, silica, sulphuric acid, 

 phosphoric acid, and chlorine ; and out of these inorganic 

 substances 20 Ibs. of the 26 Ibs. in the grain, and 46 Ibs. 

 out of the 57 Jibs, in the straw, are found to be silica, that 

 is, flint. 



Now observe this cuticle of wheat-straw.* Only look 

 at the exquisite formation of the siliceous crystals. How 

 regularly they are arranged ! how countless their number ! 

 and how beautiful their forms ! Compare them with 

 the Deutzia, and ask why such exquisite pains should 

 have been taken with the variety of these flinty forms, 

 which, but for the microscope, would never have been 

 seen. And here, too, in the cuticle of the wheat-straw, 

 we see the little stomata, or open mouths, which take in 

 * See page 252. 



