82 MEMOIRS OF 



now exists) seizes hold of some partial resemblances, with- 

 out having any regard to differences; it sees in the worm 

 the embryo of the vertebrated animal; in the vertebrated 

 animal with cold blood, the embryo of the animal with 

 warm blood ; it thus makes one class spring from the other ; 

 they are but different ages of one only ; and the whole of 

 animal life has the same phases as the most perfect indivi- 

 dual of its species. From this naturally arises the conse- 

 quence, that, taking the superior classes m an embryo state, 

 we ought there to find the inferior parts, and that the com- 

 position of all must be alike, except the greater or lesser de- 

 velopement of certain parts. But these affinities, which 

 offer something like plausibility when announced in general 

 terms, vanish directly they are detailed, and a comparison 

 is made, point by point. There is not less hiatus in the 

 affinities of parts than in the scale of beings ; in vain, in or- 

 der to escape conviction, arbitrary suppositions are brought 

 forward in the overthrow of organs incompatible with the 

 links which attach them to the rest of the body ; in vain, as 

 a last resource, is figurative language (which no logic can 

 penetrate) made use of; they are obliged to confess that 

 certain parts, often numerous, are wanting in certain be- 

 ings, without any apparent reason for their absence, other 

 than because they did not agree with the whole of the be- 

 ing ; and if in these pretended theories we seek a rational 

 nnd general basis, what is to be found except the supposi- 

 tion of a nature limited in her mode of action? 



" In fact, if we look back to the Author of all things, 

 what other law could actuate him than the necessity of ac- 

 cording to each bsing, whose existence is to be continued, 

 the means of insuring that existence ; and why could he 

 not vary his materials and his instruments? Fixed laws of 

 co-existence in organs were then necessary, but that was 

 all : for, to establish others, there must have been a want of 

 freedom in the action of the organizing principle, which we 

 have shown to be mere chimera. In vain do they have re- 

 course to that other axiom, of being obliged to make every 

 thing by the most simple means. Very far from its being 

 more simple to employ the same materials for different ob- 

 jects, it is easy to conceive some instances in which this me- 

 thod would have been the most complicated of all ; and cer- 



