148 DU. SCHLEIDEN'S THKOEY OF AGRICULTURE. 



the dice there would be triplets three times, a higli number five 

 times, and a low number tw ice, bets might be so arranged as to 

 make them on the whole successful ; and so in the long run 

 the cultivator might so jiroportion his crops as to be sure of tlie 

 eventual result in a determinate course of years, sujiposing that 

 he had any knowledge on which he could rely of the cycles of 

 weather. 



It may be perhaps worthy of remark that though man is unable 

 to exercise any influence on climate in general, he has tlie power 

 of modifying it in particular localities. Tacitus tells us that 

 no cherries, and much less grapes, would ripen in Germany, 

 speaking of the southern districts and those bordering on the 

 Rhine ; and yet the present condition of those districts, arising 

 in great measure from tlie destruction of forests, is too well 

 known to need any comment. Tlie consequence of any extensive 

 reduction of woodland tends to elevate the temperature, but the 

 results are not all so beneficial. The drying up of springs, the 

 diminution of rivers, and on the other hand sudden and destruc- 

 tive floods, are all notorious consequences. Hence the East, 

 once so richly peopled and cullivated, has half become a wilder- 

 ness, and hence the dry and barren summers of Greece and 

 Italy, in consequence of which the cultivation of clover, wliich 

 was once so rich, lias become almost impossible ; and to this 

 cause are attributable the dreadful floods which almost every 

 year desolate the banks of the Rhone. More examples might 

 easily be adduced, but these are sufficient to confirm the earnest 

 advice, " spare the forests, especially those which contain the 

 sources of your streams, for your own sakes, but more especially 

 for that of your children and grandchildren." 



B. Plants which are fixed into the soil by means of their 

 roots, and whose leaves are expanded to the air, may be con- 

 sidered as the children of both. Since the proceeds of all de- 

 composition of organic matter are volatile, the atmosphere may 

 be regarded as the great storehouse of the organic nutriment of 

 plants, as also for water, carbonic acid, ammonia, sulphuretted 

 hydrogen, and perhaps also phosphuretted hydrogen ; not, how- 

 ever, as was stated in the former part of this notice, that they 

 are immediately received from the air, but ratlier tlirough the 

 intervention of water from the ground. Indeed the ground, by 

 reason of every porous body which it contains, absorbs these 

 elements. The relations of the water contained in the atmos- 

 phere to the soil are most important as regards vegetable life. 

 If a series of dry summers be compared with the corresponding 

 produce, a great difference will be found to arise from the natuie 

 of the prevalent winds. Drought is not so much felt with a 

 course of south or soutli-west wind as with one of nortli or north- 



