INSTINCT, SENSATION, AND INTELLIGENCE. 223 



j)reservation, the same attachment to life, and resistance to destruction. For, 

 like the blood of a healthy adult, the new-laid egg, the few and simple vessels 

 of which are merely in a nascent and liquescent state, and which can scarcely 

 be regarded otherwise than as a fluid, is capable equally of counteracting 

 heat, cold, and putrefaction, and does forcibly counteract them for a consider- 

 able period longer than an egg that has been frozen or in any other way 

 deprived of its vital and instinctive principle. It is this vital and instinctive 

 principle that alone matures the egg, and shapes the matter of which it con- 

 sists into distinct and specific lineaments, and calls forth the power which it 

 does not yet possess, of sensation and perception. In what way these attri- 

 butes are produced we know not ; but we see them issuing from the matter 

 of the egg alone, when aided by the additional and cherishing power of simple 

 heat. And, provided it be properly regulated and applied, it is of no import- 

 ance from what quarter such heat is derived ; for we have already had occa- 

 sion to observe, that the warmth of a sand-bath or of an oven will answer as 

 effectually as that of the mother's sitting over it. 



But let us not rest here: let us proceed to examples of the renewal or pro- 

 pagation of life, from parent stocks ; to examples of the reproduction of the 

 ■whole, or of separate parts of the system, in cases in which there is as ob- 

 vious a destitution of sensation or intelligence ; and where, as in the pre- 

 ceding instances, the whole must be the result of pure insentient instinct. 



There is not a single organ in the animal frame but what is perpetually 

 reproducing itself, alternately dying and renewing; so that the same man of 

 to-day has not an individuarparticle belonging to him of that which consti- 

 tuted his corporeal frame ten, fifteen, or twenty years ago. And yet the 

 whole of this important change, this entire reproduction of the material sys- 

 tem, though occurring in sentient and even in intelligent organs, occurs at 

 the same time without any kind of feeling or consciousness in the individual, 

 or the organs that constitute the individual. 



This very curious fact is still more obvious in the generation of new 

 matter of every kind, — muscular, glandular, bony, and even nervous, upon 

 the death of a considerable portion of an organ in consequence of external 

 injury or other violence. The nice and admirable law by which the dead 

 substance is carried off, and its place supplied by the gradual reproduction 

 of fresh matter of the very same nature and properties, 1 have already ex- 

 plained.* In the separation of the dead from the living parts, there is gene- 

 rally, though not always, some degree of pain, from the increased local action 

 that takes place, and more especially from the tension given to the skin by 

 the secretion of sound and healthy pus, in order to effect its bursting; but in 

 the actual generation of the new material that is to fill up the cavity, and 

 supply the place of what is lost, there is no pain or sensation whatever in a 

 healthy process ; while, as I have likewise "already observed, the pointing of 

 the abscess, like the pointing of the seeds of peas or beans, in what direction 

 soever they are sown, will be uniformly towards the surface,! whatever be 

 the obstacles that must be overcome in order to reacli it. 



The generation of life, then, no more necessarily demands or implies the 

 existence of sensation, than attachment to life, or a self-preserving principle : 

 it may be combined with it, but it may also exist separately or without it. 

 Monro, indeed, has distinctly proved by experiment, that the limb of a frog 

 can live and be nourished, and its wounds healed, without any nerve what- 

 ever, and, consequently, without any source or known possibility of sensation. 



Let us apply this reasoning, which I admit is thus far drawn from individual 

 parts of the system alone, to a regeneration or reproduction of the entire system. 



The lungs or gills of an animal are precisely analogous to the leaves of a 

 plant. All these, as I have already observed, are perpetually changing by a 

 nicely balanced .alternation of decay and reproduction. In animals and ever- 

 green plants this change is so gradual as to elude all notice. In deciduous 

 plants, on the contrary, it is sudden and obvious to every one ; yet the same 



• Series i. Lecture xlv. | Series n. Lecture iT. 



