The object of this paper was to fix attention on the great physiological discovery which has been gradually effected during the present century, of the mode in which certain of the elements contained in the earth's atmosphere, under the influence of light and of a certain temperature, are continually employed in maintaining that great vital circulation, of which vegetable structures, animal structures, the air, and the soil, are the successive links; and to point out that the most essential and fundamental of the changes here effected,—particularly the formation of the different organic compounds in the cells of vegetables,—are strictly chemical changes, at least as clearly distinct from any chemical actions yet known to take place in inorganic matters, as the vital contractions of muscles are distinct from any merely mechanical causes of motion; and justifying the statement of Dr Daubeny, that there appears to be “a power, residing in living matters” and producing chemical effects,—in fact manifesting itself most unequivocally by the chemical changes which result from it,—“distinct, at least in its effects, from ordinary chemical and physical forces.”