19 



chain of ganglions*, stigmas, and tracheae, analogous to the respiratory 

 organs of plants, and in some, even gills : all shows clearly an organiza- 

 tion further advanced, and more perfect : sensibility and contractility are 

 more distinct; the motions are no longer absolutely automatic : there are 

 some which seem to suppose a choice. The worm, too, may be divided 

 into many pieces ; each will become a separate and perfect worm; a head 

 and tail growing to eachf; but this division has its term, beyond which 

 there is no longer complete regeneration. It cannot, therefore, be push- 

 ed so far as in the polypi. The substance of the* worm being formed of 

 elements more dissimilar, it may be that too smal] a portion does not con- 

 tain all that is necessary to constitute the animal. 



The crustaceous tribes, and among them the lobster, discovers a more 

 complex apparatus of organization. Here you will find distinct muscles, 

 an external articulated skeleton, of which the separate parts are move- 

 able upon each other, distinct nerves, a spinal marrow with bulgings, but, 

 above all, a brain and a heart. These two organs, though imperfect, as- 

 sign the animal to an order much above that of worms. The first be- 

 comes the seat of a sort of intelligence ; and the lobster acts evidently 

 under impulses of will, when attracted by a smell, it pursues a distant 

 prey, or when it flies a danger discovered to it by its eyes. There are 

 viscera accompanying the intestinal tube, which give out to it liquids 

 that concur in alimentary digestion. Sensibility and contractility pre- 

 sent each two shades : in fact, the parts of the animal are obedient to the 

 internal stimuli, feel the impression of fluids, and contract to impel them ; 

 on the other hand, by its nerves and locomotive muscles, the lobster 

 places itself in connection with the objects that surround it. The phe- 

 nomena of life are linked together by a strict necessity: it is no longer 

 possible to separate the creature into two parts, of which each may con- 

 tinue to live; there are but few parts you may cut off without injury, 

 while you spare the central foci of life. So, if you take off a claw, you 

 observe soon a little granulation, which swells and is developed, and 

 which, soft at first, is soon clothed in a calcareous covering like that 

 "which encloses the rest of its body. This partial regeneration is fre- 

 quently to be seen. 



If from white-blooded animals we go on to the red and cold-blooded, 

 such as fishes and reptiles, we see this power of reproduction becoming 

 more and more limited, and life more involved in organization. In fact, 

 if you cut off a part of the body of a fish, the tail of a serpent, or the foot 

 of a frog, the separated parts are either not supplied at all, or very im- 

 perfectly reproduced. All these creatures maintain, with the medium in 

 which they live, relations of more strict dependence. Gills in these, lungs 

 in others, are added to a heart, nor are less essential to life. However, 

 the action of these chief organs is not so frequent, nor of momentary ne- 

 cessity for the continuance of life. The serpent passes long winters, tor- 

 pid with cold, in holes where he has no air, without breathing, without any 

 motion of life, and in all appearance dead. These creatures, like all rep- 

 tiles, are able to breathe only at long intervals, and to suspend, for a 

 time, the admission of air, without risking their existence. Here the 



* Appendix, Note B. 



f This may be observed tn several of the intestinal worms. It ought to be kept in 

 recollection during our endeavours to remove them from the body Copland, 



