VEGETABLE PHYSIOLOGY. 



positive, in the third, electro-polar. Any individual object or body may be positive 

 to another, whilst it is negative to a third. Hence the absolute electric state that 

 any body can appear in is in the polar — a condition growing plants must necessarily 

 assume. A similar inequality of electric force occurs among growing plants and 

 their manures, and even amongst the various elements which constitute the latter, 

 DO two of them being precisely alike at the same time. Hence the particles con- 

 stituting each and every variety of soil, are endowed with a peculiar electric force 

 — a circumstance of immense importance in the contemplation of the vegetable 

 physiologist. 



" The metals are the best electrical conductors, but there are many other kinds 

 of matter which rank high in this capacity ; such are trees when full of sap-water, 

 and consequently all growing plants by virtue of the water they contain. Moist 

 land is also a conductor of electricity. Dry sand is a bad conductor ; so is dry 

 mould of every kind; but limestone rock and dry chalk are still worse; and dry 

 air is a worse conductor than any of the rest, though moist air is a tolerably good 

 conductor. 



"Another grand law of electricity is, that the transmission is uniformly from 

 the positive to the negative parts. Now, as this is a universal law when electric 

 fluid is transmitted from one body or object to another, it follows that the electro- 

 positive state of the air, contiguous to growing plants, causes the latter to become 

 electro-polar, even when they are in the act of transmitting fluid to the ground, 

 their upper parts being negative, relative to the roots, whilst the latter, in their 

 turn, are positive to the contiguous manure and soil, to which they deliver up the 

 fluid, or, rather, such portions of them as are not retained for the expansion and 

 growth of the plants. 



"From this train of reasoning, we are led to some of the most interesting points 

 in vegetable physiology. The electro-polar condition of plants qualifies them, in 

 an eminent degree, for the performance of those operations which develop electro- 

 chemical phenomena, and, what is very remarkable, the laws of this beautiful 

 branch of electricity are rigidly enforced, and admirably complied with in the 

 decomposition of carbonic acid gas by their foliaceous parts; for, in this process, 

 the electro-positive carbon is drawn to the electro-negative poles of the plants in 

 precisely the same manner as any electro-negative pole, artificially made, would 

 release the carbon from the oxygen, and select it in preference. This remarkable 

 fact, based as it is on the strict principles of electric action, not only establishes 

 a correct view of the modus operandi by which plants are enabled to acquire food 

 through the instrumentality of their foliage, but appears to be well calculated to 

 give a clue to every operation by which vegetables become nourished, and elaborate 

 their food, in all the variety of structure they so beautifully assume. 



" Contemplations on electro-chemical forces, thus disencumbered of complexity, 

 lead by easy gradations to many recondite operations of nature, and to the dis- 

 covery of those hidden actions by which the ever-varying transformations of mat- 

 ters are accomplished. They are well calculated to afi'ord a clue to those atomic 

 operations which, in silent reclusion, select the appropriate materials, convey them 

 to their destination, and elaborate them in the structure of every vegetable tissue 

 that is found within and upon the land." 



Here, then, this theory, for its simplicity and adaptation, challenges our consent 

 — no roundabout way of attaining an end ; for if the former were the true one, 

 and all matters necessary for growth, had to be conveyed to the leaves to be or- 

 ganized or fitted for assimilation, we might reasonably suppose that the deposition 

 of woody matter would be greatest near the leaves soon after it was prepared. 

 ~ e know the reverse of this is the fact, and very wisely has it been so decreed. 



