114 PARTICULAR CONSIDERATIONS ON THE 



of the electric fluid. In the marks caused by positive electricity, 

 or which it leaves in its passage, we see the ramifications of a 

 tree, as well as of its individual leaves ; those of the negative, 

 recal the bulbous or the spreading root, according as they are 

 clumped or divergent. These phenomena seem to indicate 

 that the electric energies have had something to do in deter- 

 mining the forms of plants. With regard to the resemblance 

 of the ramifications of the branches and leaves of plants to the 

 traces of the positive electricity, and that of the roots to the 

 negative, it is a circumstance calling for especial remark, that 

 the atmosphere, particularly its lower strata, is generally 

 charged positively, while the earth is always charged nega- 

 tively. The correspondence here is curious. A plant thus 

 appears as a thing formed on the basis of a natural electrical 

 operation the brush realized. We can thus suppose the various 

 forms of plants as determined under the operation of a ]aw in 

 electricity, variously affecting them according to their organic 

 character, or respective germinal constituents. In the poplar, 

 the brush is unusually vertical, and little divergent ; the reverse 

 in the beech : in the palm, a pencil has proceeded straight up 

 for a certain distance, radiates there, and turns outwards and 

 downwards ; and so on. We can here see at least traces of 

 secondary means by which the Almighty Deviser might esta- 

 blish all the vegetable forms with which the earth is over- 

 spread. 1 



1 " the form of the route of free electricity is modified by the 



medium through which it passes, and also by the electrical state of such 

 medium, or of that of the relative electrical conditions of two bodies 

 between which it is transmitted. If the medium through which it passes 

 possesses a very inferior conducting power, it is obvious that a certain 

 momentum must be requisite to enable the fluid to force its passage to a 

 given distance, and there will be a point at which the momentum of the 

 fluid and the resistance of the body will exactly counterbalance each 

 other ; but so soon as the electricity has again accumulated to a suffi- 

 cient degree to overcome the resistance, it will again force its way in 

 another direction, until it arrives at another point of equilibrium. In 

 this way we may readily see the modus operandi of the electric fluid in 

 imparting regular forms to bodies; and it is highly probable that its 

 action in this respect extends to the vegetable kingdom, and perhaps operates 

 even on animals, from the time in which they exist in the embryo state. . . . 

 Another fact, in support of the opinion that the distinctive forms of 

 bodies are produced by electrical action, is, that crystals, and the twigs 

 and leaves of vegetables, all terminate in points or sharp edges, so that 

 the electrical action can proceed no further in increasing the growth, or, 

 in other words, in propelling fresh portions of matter for the extension 

 of the plant, or the crystal, beyond the pointed or edged termination." 

 Leithead on Electricity, 1837. 



