THE PLANT _grows_, not by the gathering together of similar particles of matter, but by the absorption of a compound particle--by that one which must be regarded as the primary nuclear atom or cell. After this absorption--in virtue of a power which we call LIFE, excited into action by LIGHT--the compound particle is decomposed, and one constituent is retained to effect the formation of a new cell, whilst the other is liberated as an invisible air. Here we have a change of chemical constitution effected; and this takes place through the whole period of vegetable growth, from the development of the plumule up to the formation of the latest leaf upon the topmost branch of the most lordly tree. Life has been referred to electricity and to chemical power--as the effect of a known cause. Without doubt, during the operations of life the whole of the physical powers are necessary to the production of all the phenomena of growth in the vegetable and the animal world. But these powers are ever subsidiary to vital force, and are like attendant spirits chained to do an enchanter’s bidding. Life is a force beyond the reach of human search, and he who fancies he has a hold upon the principle which produced biological phenomena, has committed himself to as wild a pursuit as he who rashly endeavours to catch a morass-meteor. Subtile as are the forces of light, heat, and electricity--that of life, _vitality_, is infinitely more refined, and it must for ever elude the search of the philosopher. Man is permitted to test and try all things which are created, and to apply to useful ends the discoveries which he may make. But man can never become a creator; and he who would attempt to give sense to an inert mass of matter, by electricity, heat, or light, will prove himself as ignorant of nature’s truth as is the senseless mass upon which he works. “So far shalt thou go, and no further,” was said equally to the great tide-wave of human intellect, as to the mighty surge of the earth-girdling ocean. It must not be forgotten that a striking difference exists between the productions of the mineral and the other kingdoms of nature. Animals and vegetables arrive at maturity by successive developments, and increase by the assimilation of substances, having the power of producing the most important chemical changes upon such matter as comes within the range of their influence; but minerals are equally perfect in the earliest stages of their formation, and increase only, as previously said, by the accretion of particles without their undergoing any change. The animal and vegetable tribes cease to continue the functions of life: death ensues, and a complete disorganisation takes place; but this is not the case in the mineral world: the crystal being the result of a constantly acting force is not necessarily liable to decomposition.