■ i7i their Structure and Functions, 127 



in other words, it is inferred that plants can have no gan- 

 glionic nerves by which their conservative functions are in- 

 fluenced. This, probably, might have been the case, if the 

 functions of plants had consisted merely of circulation and 

 respiration; but we cannot for a moment suppose it to be so 

 when we consider that the vegetable functions consist of ca- 

 lorification, of absorption, of assimilation, of sanguification, 

 of secretion, and of generation. If these functions require 

 to be regulated and connected together by a circle of nerves 

 in animals, surely they require the same bond of union and 

 regulating power in plants, in which they are conducted on 

 the same principle as in the animal system. The most con- 

 clusive proof that vegetables are endowed with ganglionic 

 nerves is their power of generating heat. Sir E. Home 

 has discovered that animal heat is not produced by every 

 part of the nervous system, but only by the ganglionic 

 nerves. He observes that the temperature of those ani- 

 mals which possess only a brain, or some part equivalent 

 to it, never exceeds that of the medium in which they 

 are immersed; while those whose temperature is always 

 found greater than that of the medium which surrounds them 

 are supplied with ganglia. The ganglionic nerves appear then 

 to possess the specific faculty of generating heat. If then 

 animals derive their power of creating heat from the gan- 

 glionic nerves, it is to be presumed that vegetables, which are 

 endued with the same power, obtain it from the same source. 

 There can be no doubt, therefore, (and it is more consistent 

 with our ideas of the general harmony of nature to suppose,) 

 that plants possess gangUonic nerves, and, of course, that 

 peculiar sensation dependent on these nerves ; not sensation 

 with perception, but that state of consciousness, or pleasurable 

 feeling, to which the name of health has been applied. The 

 conjecture which I have advanced respecting the existence of 

 ganglionic nerves in plants has been corroborated by the testi- 

 mony of M. Brachet. This eminent physiologist, in a work 

 entitled Recherches Eocperimentales sur les Fonctions du Systeme 

 Nerveux Gangtionnaire, &c., which was only for the first time 

 made known in England in January last (six weeks after my 

 paper had been read to the Hull Literary and Philosophical 

 Society), expresses the belief that vegetables have the faculty 

 of sensibility, and that this sensibility is derived from a gan- 

 glionic system of nerves, which, by a variety of experiments 

 and arguments, he has satisfactorily proved they possess. 



Sir J. E. Smith, too, conceived that plants are endued with 

 sensation, although he makes no allusion to their possessing 

 either ganglionic or any other kind of nerves. In his Intro- 



