THE VEGETABLE AND ANIMAL KINGDOMS. 137 



tadpoles of Batrachia ; the breathing organs and chief parts 

 of the alimentary apparatus were aggregated with the proper 

 viscera of the cranial cavity in an enormous cephalic enlarge- 

 ment ; the rest of the trunk was for locomotion, and dwindled 

 to a point. The position of the anal fin proves the vent to 

 have been situated, as in tadpoles, immediately behind the 

 cephalic abdominal expansion. In the Pterichthys, the mouth 

 was small and inferior, as in the young tadpole ; and there are 

 long fin-like appendages, projecting from the sides of the 

 cephalic enlargement, like the external gills of the Batrachian 

 and Selachian larvae." 1 Other examples of this curious analogy 

 have already been enumerated from the pages of another 

 eminent physiologist. The subject is as yet in much need of 

 elucidation ; but the leading idea has certainly been made 

 tolerably clear. 



Now it will occur to all who can approach this subject with- 

 out prejudice, that, if there be a real identity of character in the 

 two sets of phenomena, there is in that fact a great improbabi- 

 lity that the two sets of phenomena have been produced by two 

 different kinds of causes that the development of a particular 

 organism is a natural phenomenon, but that the development of 

 the whole animal or vegetable kingdom has taken place under 

 different conditions. It must appear, on the contrary, highly 

 likely that the producing, ruling, and guiding cause operated 

 in the same manner in the two cases. Neither can it be 

 irrational to suggest that embryonic development shadows 

 forth the principle which was employed or followed by the 

 Uncreated, in filling the earth with the organic creatures by 

 which it is inhabited. 



Does it not now appear as if the clouds were beginning to 

 give way, and the light of simple unpretending truth about to 

 break in upon the great mystery ? In the first place, however, 

 let us remember that, in such speculations, the explanation 

 which is most simple, and which makes the least demand upon 

 the puerile emotion of wonder, is always, other things being 

 equal, the most acceptable. In physiology, particularly, a 

 phenomenon of slow and gradual movement must ever have an 

 advantage over one which consists in a great and sudden effect, 

 because all the observable processes in physiology are of the 

 former character. Supposing that the reproduction of living 

 beings say, for example, trees were, from the invisibility of 



1 [Professor Owen ?] Quarterly Keview, Sept. 1851. 



