320 ANIMAL NATURE AS A WHOLE. [iii. 



and other ganglia/ unfelt external impressions are reflected, 

 in accordance with the objects of nature, upon those nerves 

 through which the nerve-actions appropriate to the impressions 

 are induced, and in which certain non-conceptional internal 

 impressions (internal stimuli of the nervous fluid) induce or 

 maintain, by means of the mechanism of the animal, various 

 animal movements necessary to its existence, well-being, &c.; 

 but which cannot be induced, at least solely, by external im- 

 pressions. Such a brain could be no more the seat of mind, 

 than the spinal cord or the ganglia. Haller, quoting the ob- 

 servations of Swammerdam and Lyonnet, as to the great 

 simplicity of structure of the small ganglion in lobsters and 

 caterpillars, termed a brain, and its great similarity to the other 

 ganglia, adds, that even in fishes and cold-blooded animals, the 

 brain appears to be only an appendage to the spinal cord. 

 ('Physiology,^ vol. iv, p. 6.) 



V. Because, all the proofs which are adduced to show that 

 certain nerve-actions in sentient animals are not sentient actions 

 (129, 130), are equally valid here. All the conditions necessary 

 to sentient actions are wanting in animals without a brain, or 

 with a brain of the kind just referred to, and in which no ma- 

 terial ideas are produced. There is medullary substance in all 

 the nerves ; the spinal cord is for the most part made up of it, 

 and yet in neither are the material ideas of conceptions ever 

 formed. 



625. All these grounds taken together, render it extremely 

 probable, that such animals are constituted insentient by nature, 

 and endowed with vis nervosa only, so as to be fitted for all the 

 objects of their existence. We will deduce no arguments in 

 favour of this doctrine, from the nature of the soul, so totally 

 unknown to us, nor will we answer any objections brought 

 against it from the same source, for what can be adduced where 

 we are so completely in the dark ? There is the same difficulty 

 in explaining how a pure soul develops animal movements, 

 whether the body through which it operates be a skilfully con- 

 structed mechanism, or mere matter. Nature has prescribed 

 this law to them, on grounds entirely unknown to us, and it 

 remains with her, whether all or only a few animals be endowed 



' Compare note to § 35. — Ed. 



