464 AGRICULTURAL REPORT. 



GEOGRAPHY Of PLANTS. 



OUTLINE SKETCH OF THE GEOGRAPHY OF PLANTS AND OF THE METHODS PRO- 

 POSED FOR DETERMLNLXG THE AMOUNT OF HEAT REQUIRED BY THE VINE 

 AND THE WHEAT PLANT; WITH REMARKS ON THE PRODUCTION OF NEW 

 VARIETIES OF WHEAT, AND ON THE ACCLIMATION OF PLANTS, AND OBSERVA- 

 TIONS ON THE NECESSITY OF A MORE ENLIGHTENED AGRICULTURE. 



BY JAMES S. LIPPINCOTT, HADDONFIELD, NEW JERSEY. 



The most superficial observer has doubtless sometimes noticed a method in 

 the arrangement of natural objects, and believes that they have not been dis- 

 tributed by chance, or left without the superintendence of a directing agency. 

 He perceives, if his view becomes more extended, that they have not been 

 scattered at random over the surface of the globe. He who is better informed 

 has learned that living beings (animals and plants) are regulated in their dis- 

 tribution by especial laws, and that their arrangement gives to each country a 

 peculiar aspect. 



The pliysical conditions which seem to regulate this distribution of living 

 beings are diversified, and are mostly included under the idea of climate. 

 Among the agencies which are understood to influence the life, health, develop- 

 ment, and extension of the range of animals and plants, the more important are 

 the distribution of heat throughout the year, its periodic increase and diminu- 

 tion, the conditions of humidity or dryness of the air and of the soil, the amount 

 of light, the electric conditions, and in some instances the pressure of the atmo- 

 sphere, and the varying degrees of actinic power or force of the chemical rays 

 of the sun. 



There are other very important considerations affecting the distribution of 

 plants, which are not properly included under our idea of climate. Among 

 these may be enumerated the composition and chemical character of the soil, 

 which are influenced by the rock whence it was derived ; the mechanical con- 

 ditions of the soil, whether friable or coherent, readily decomposed, or resisting 

 decomposition in a state of fine comminution, or in coarse grains or gravel ; 

 permeable readily by heat, rain, or moisture, or otherwise ; and, finally, on the 

 amount of vegetable matter therein, the color of the soil, and its inclination and 

 exposure to the rays of the sun. The art of the agriculturist enables him to 

 modify all these latter-named circumstances, and to adapt the soil to his various 

 needs ; but the vicissitudes of the climate he cannot control — over the wcatlier 

 he has not been made master. 



The most important climatic influence is temperature, which, indeed, in this 

 association may be termed the dominant power. It is beneath the ardent rays 

 of a tropical sun that the noblest forms of vegetation are developed, while in the 

 circumpolar zones neither trees nor shrubs can exist, and extensive districts 

 are entirely destitute of plants, or in favored spots alone are found a few lichens 

 and diminutive herbs, which the short summer of these regions calls forth from 

 the partially thawed surface of the deeply frozen ground. Between these nobk 

 products of the torrid zone and the almost barren desolation of the Arctic 

 regions there exists every variety of vegetable form, growing gradually less 

 diversified and generally more dwarfish as we approach the limits of existence 



