28 INTRODUCTION. 



general ideas which we form respecting this process are tolerably clear, although we 

 have no distinct or detailed notion of what passes at each point ; and for want of 

 knowing the chemical composition of each part with sufficient precision, we cannot 

 render an exact account of the transformations necessary to produce it. 



Besides the glands which sepjarate from the blood those fluids which perform some 

 office in the internal economy, there are some which detach others from it that are to 

 be totally rejected, either simply as superfluities, such as the urine, which is produced 

 by the kidneys, or for some use to the animal, as the ink of the cuttle, and the purple 

 matter of various other mollusks, &c. 



With respect to generation, there is one process or phenomenon infinitely more 

 difficult to conceive than tliat of the secretions ; it is the production of the germ. We 

 have seen even that it may be regarded as little less than incomprehensible ; but, the 

 existence of the germ once admitted, generation presents no particular difficulty : so 

 long as it adheres to the parent, it is nourislicd as if it were one of its organs* ; and 

 when it detaches itself, it has its own proper life, which is essentially similar to that 

 of the adult. 



The germ, the embryo, the fcetus, and the new-born animal, have in no instance, 

 however, precisely the same form as the adult, and the difference is sometimes so great, 

 that their assimilation merits the name of metamorphosis. Thus, no one not previously 

 aware of the fact, would suppose that the caterpillar is to become a butterfly. 



All living beings are more or less metamorphosed in the course of their growth, 

 that is to say, they lose certain parts, and develope others. The antennae, wings, and 

 all the parts of the butterfly were inclosed within the skin of the caterpillar ; this 

 skin disappears along with the jaws, feet, and other organs that do not remain in the 

 butterfly. The feet of the frog are inclosed by the skin of the tadpole : and the tad- 

 pole, to become a frog, loses its tail, mouth, and gills. The infant likewise, at birth, 

 loses its placenta and envelope ; at a certain age its thymous gland almost disappears ; 

 and it acquires by degrees its hair, teeth, and beard. The relative size of its organs 

 alters, and its body increases proportionally more than its head, its head more than its 

 internal ear, &e. 



The place where these germs are found, the assemblage of them, is named the ovary ,- 

 the canal through ■\\hich, when detached, they are carried forward, the oviduct ; the 

 cavity in which, in many species, they are obliged to remain for a longer or shorter 

 period before birth, the matrix or vtcrus ; the exterior orifice through which thej' pass 

 iuto the world, the vulva. When there are sexes, the male sex fecundates ; the germs 

 appearing in tlie female. The fecundating liquor is named semen ; the glands which 

 separate it from the blood, tenticles ; and, when it is necessary that it should be intro- 

 duced mto the body of the fcra;de, the intromittent organ is called s. penis. 



RAPID EXPOSITION OF THE INTELLECTUAL FUNCTIONS OF ANIMALS. 



The impression of external objects on the jie, the production of a sensation, of an 

 I image, is a mystery impenetrable to our intellect ; and materialism an hypothesis, so 

 j much the more conjectural, as philosophy can furnish no direct proof of the actual 



