the Animal Kingdom. 349 



intestine, like the vesicula umbilicalis ? In Mammals, the in- 

 cisors are the teeth which first appear ; but no animals have 

 permanently fore-teeth alone. 



The same author has well remarked, that inasmuch as em- 

 bryonal relations produce forms that are present in no grown 

 animal, such as the pendant intestinal sac, just mentioned ; it is 

 also impossible that any embryo can repeat the state of many 

 groups of animals. All embryos are surrounded with fluid; 

 and consequently incapable of immediately respiring air. The 

 real character of insects, therefore, a lively relation to the air, 

 can never be repeated in an embryo. For the same reason, 

 the embryo of mammals can never resemble perfect birds.* 



Besides these arguments, there are others ; but it is by no 

 means needful to bring forward more. We briefly recapitulate 

 those now advanced. 



\stly, There does not exist a scale of structure, differing in degree alone. 

 2dly, Individualities cannot be laid aside. Sdly, There exist permanent struc- 

 tures among the so-called " lower " animals, not met with in the embryonal 

 phases of any of the " higher." 4thly, There are many phases of the " high- 

 er" animals, corresponding to which, we do not find any permanent structures 

 among the " lower." 5thly, No structure peculiarly characterizing any one 

 set of animals in the perfect state, makes its appearance even in the embry- 

 onal life of any other. Lastly, The sum of the innate susceptibilities of struc- 

 ture is not the same in any two germs. 



It has been said,-f- that " the assertion is nothing more than 

 that Man, as Man, has once in the progress of his development, 

 been upon that grade upon which the several classes beneath 

 him remain stationary in the progressive development of the en- 

 tire animal kingdom." But even thus qualified, it is by no 

 means true. Man, in the progress of his development, is not 

 upon that grade on which any other animals remain stationary, 

 unless the latter belong to the same type as man : { and even then, 

 the resemblance would relate to certain parts only, because each 

 order, family, genus, species, variety, sex, and individual, has 

 its own peculiarities, which are repeated in the structure of no 

 other animal. 



* 1. c. p. 204. 



f Burmeister's Entomology, translated by Shuckard, 3vo, 1836, p. 419. 



$ We admit, indeed, that the whole animal kingdom has essentially the 

 same fundamental or merely animal form ; but from this there is an imme- 

 diate divergence. (See Fig. 12, p. 346.) 



