42 INTRODUCTION. 



of the formation or production of animals; they possess also, 

 although in a less degree or less general manner than vegeta- 

 bles, the faculty of reproducing by a kind of vegetation, parts 

 which have been cut off or destroyed ; but the faculty is not 

 even in the same degree in every animal: The simplest ani- 

 mals in organization possess it in the greatest perfection. The 

 polypi, and especially the hydra, always reproduce those por- 

 tions which have been cut off, so that, individuals are multi- 

 plied by the simpleact of division of parts. The power of repro- 

 duction of the actinia is no less extensive; they reproduce 

 parts which have been taken away, and are multiplied by the 

 division. The asterias have also a great power of reproduc- 

 tion ; they again produce the rays which are destroyed; even 

 when a single ray, provided it be entire, can reproduce the 

 others. The faculty possessed by the toenia of reproducing 

 the posterior rings of their body is well known. Among the 

 annulosa, the nereides has also a very great power of repro- 

 duction. Experiments have been performed on the lobster, 

 which went to prove the power possessed by this animal of 

 shooting out a new foot whenever it has been injured by acci- 

 dent. It seems that the arachnides also have the faculty of re- 

 generating legs which they have lost. The aquatic salaman- 

 ders have also an astonishing power of reproduction; they 

 shoot out several times in succession the very same limb when 

 cut, and that too, with its bones, muscles, vessels, &c. The 

 limbs and tails of the tadpole of the frog is also regenerated 

 very much like those of salamanders. The tail of the sauria, 

 when torn off, grows again, although sometimes a little differ- 

 ent from the first one. In warm blooded animals the power 

 of reproducing parts which had been removed by excision, 

 is almost confined to epidermic or horny parts. As to the 

 other parts, this power does not extend beyond the healing of 

 wounds, and the production of a cicatrice analogous to the skin, 

 when this latter is cut off or destroyed. 



The organs and functions belonging to animals, present, like 

 the preceding, many degrees of complication or varieties in 

 the beings which compose the animal kingdom. 



27. In the simplest animals the body being, or appearing 





