494 [Assembly 



pie, hy a mo7'e vigorous growth^ usurp its ancient place, The ori- 

 ginal distribution of oar forest trees is worthy of more careful 

 attention than we are bestowing on it, and it is to be hoped that 

 they will receive it before the progress of civilization shall have 

 effaced the limits of thc4r different regions. 



As the plants on which man and the domestic animals subsist 

 belong to tliose varieties that require a rich soil, this progression 

 favors tliem, and consequently the increase of population, and SO 

 we come to have interests vested in these plants as lively as our 

 interests in our own welfare ; we come to study their habits and 

 to inquire on what meat they feed. 



Premising the germ, the beams of the sun build up the struc- 

 ture of plants out of four classes of substances : 



I. Water. — This substance is the natural diluent of the juices, 

 and is the medium of all circulation. The material of which 

 every plant is composed must once have been dissolved in water 

 — dissolved in it, too, without any aid from the vital forces of tliB 

 plant, as simple as sugar is dissolved in water — ^in this condition 

 must have entered its tissues, and out of this solution must have 

 been revived in the insoluble form by the action of the sun on tlie 

 leaf. The amount of water that is drawn in twelve hours from 

 the earth by a plant and exhaled into the air in summer is enor- 

 mous. Hales found that a sunflower that weighed 3 lbs. in that 

 time exhaled 20 ounces on an average. If, then, a crop of hay 

 weigli one ton to the acre dry and ten tons to the acre green, it 

 would exhale nearly six tons of water per day, an amount amply 

 sufficient to furnish it with its saline constituents in any common 

 condition of this water. There is a connection in this way in 

 plants as there is in animals, between the amount of water and 

 the amount of salts they consume. In addition to this mechani- 

 cal use of water, it must be decomposed, its atoms must be split 

 in some way in the plant, and there is no other source of the hy- 

 drogen that is combined with the carbon of the vegetable oils. 

 The economical uses of water, and the way in which it may be 

 made to substitute saline top dressings, were alluded to on a for- 

 mer occasion. 



