OF ANIMALS. 



respond with the organ of a brain. The nervous chord, however, in these 

 animals is, for the most part, proportionally larger than in those of a su- 

 perior rank ; and at various distances is possessed of little knots or gan- 

 glions, from which fresh ramifications of nerves shoot forth, like branches 

 from the trunk of a tree, and which may perhaps be regarded as so many 

 distinct cerebels or little brains. 



In zoophytic worms, we can scarcely trace any distinction of structure, 

 and are totally unable to recognise a nervous system of any kind. The 

 common and almost transparent hydra or polype, which is often to be found 

 in the stagnant waters of our own country, with a body about an inch 

 long, and arms or tentacles in proportion, appears to consist, when exa- 

 mined by the best glasses, of nothing but a granular structure, something 

 like boiled sago, connected by a gelatinous substance into a definite form.* 

 Hydatids and infiisory animals exhibit a similarity of make. The common 

 formative principle of all these may be reasonably conjectured to consist 

 in the living power of the blood alone, or rather of the fluid which answers 

 the purpose of blood ; and their principles of action to be little more thaii 

 instinctive. 



Can we, then, conceive that all these diflferent kinds, and orders, and 

 classes of animals, thus differently organized and diflJerently endowed with 

 intelligence, are possessed of an equahty of corporeal feeling ? or, to adopt 

 the language of the poet, that — 



— the poor worm thou tread'st on, 



In corporeal suffering, feels a pang as great 

 As when a giant dies ? 



This is an interesting question, and deserves to be examined at some 

 length. It may, perhaps, save the heart of genuine sensibility from a few 

 of those pangs which, even under the happiest circumstances of life, will 

 be still called forth too frequently ; and if there be a human being so 

 hardened and barbarized as to take advantage of the conclusion to which 

 the inquiry may lead us, he will furnish an additional proof of its correct- 

 ness in his own person, and show himself utterly unqualified for the dis- 

 cussion. 



Life and sensation, then, are by no means necessarily connected : the 

 blood is alive, but we all know it has no sensation ; and vegetables are 

 alive, but we have no reason to suppose they possess any. Sensation, so 

 far as we are able to trace it, is the sole result of a nervous structure. 

 Yet, though thus limited, it has already appeared that it does not exist 

 equally in every kind of the same structure, nor in every part of the same 

 kind. The skin is more sensible to pain than the lungs, the brain, or the 

 stomach ; but even the skin itself is more sensible m some parts than in 

 others, which are apparently supphed with an equal number of nerves, 

 and of nerves from the very same quarter. It is perhaps least sensible in 

 the gums ; a little more so on the hairy scalp of the head ; much more so 

 on the front of the body, and most of all so in the interior of the eyelids : 

 while the bones, teeth, cartilages, cuticle, and cellular membrane, though 

 largely supplied with nerves, have no sensation whatever in a healthy 

 state. 



As the degree of intelligence decreases, we have reason to believe that 

 the intensity of touch or corporeal feeling decreases also, excepting in 

 ^articular organs^ in which the sense of touch is employed as a local 



* Blumenb. Anat. Comp. § 202, 



