FRUITFULNESS AND BARRENNESS OF PLANTS. 
37 
leaves and brandies are made conformable to the most perfect and 
symmetrical designs: the practice of gardening can be little more 
than the assisting of nature in the attainment of her ends, by sup¬ 
plying her with the required nourishment, and affording her support 
and protection against casual obstructions and injuries. To obtain 
the desired results of horticulture, therefore, our principal care must 
be so to regulate the operations of art, as that they may be in perfect 
harmony with the laws of nature: and as it is of the highest impor- 
tance that these Should be firmly imprinted on the mind, we shall 
first recapitulate and arrange the laws of nature to which the princi¬ 
pal effects are traceable. They may be comprised under the thir¬ 
teen following divisions: 
1st. The generating, or first forming of a plant, or impregnation 
of the seed with the living principle, requires the junction of two dis¬ 
tinct parts or productions of the blossom or flower ; that is, it is re¬ 
quired by nature that the pollen or dust produced by the anthers be 
brought in contact with, or placed on, the crown or summit of the 
pistil. 
2nd. To enable the pollen to impregnate the seeds with the living 
principle, a certain degree of heat is necessary, according to the na¬ 
ture of the plant; some requiring a greater and some a less; but 
most plants require a degree of heat above 50° Fahrenheit’s ther¬ 
mometer, when placed in the shade, and that the sun should shine 
on them for two or three hours, during some part of the day, for four 
or five days following, when in bloom, for the purpose of performing 
the office of incubation and hatching the globules which form the 
pollen. And it is allowed by nature that the pollen of one plant, 
when thus brought in conjunction with the pistil of another plant, 
although a variety of the same species, shall produce the like effect 
of impregnation ; and that the progeny of the two plants shall in 
some degree partake of the peculiar characteristics of both of them. 
3rd. To vegetate seeds, or give the necessary impulse to the living 
principle, and put it into action, a due quantity of water, and a due 
supply of oxygen, or a free access of the atmospheric air, and a de¬ 
gree of heat above 50° Fahrenheit, are necessary. 
4th. Plants, like animals, require a constant supply of food to sus¬ 
tain them; and as from their peculiar formation, plants cannot con¬ 
sume or take any thing into their bodies but in a state of liquid, 
water, holding in solution a certain portion of carbonaceous matter 
and earth, constitutes the nutriment or food of plants; and a con¬ 
tinued supply, change, or circulation of water in the soil, is necessary 
to sustain the life of plants, and to preserve them in health and vigour. 
