f 
a PHENOMENA OF ORGANIC NATURE = 325 
fore-leg of the horse or the dog, or the ape or 
man; and here you will notice a very curious 
thing,—the hinder limbs are absent. Now, let 
us make another jump. Let us go to the codfish: 
here you see is the forearm, in this large pectoral fin 
—carrying your mind’s eye onward from the flapper 
of the porpoise. And here you have the hinder 
limbs restored in the shape of these ventral fins. 
Tf1I were to make a transverse section of this, I 
should find just the same organs that we have 
before noticed. So that, you see, there comes out 
this strange conclusion as the result of our 
investigations, that the horse, when examined 
and compared with other animals, is found by no 
means to stand alone in Nature; but that there 
are an enormous number of other creatures which 
have backbones, ribs, and legs, and other parts 
arranged in the same general manner, and in 
all their formation exhibiting the same broad 
peculiarities. 
I am sure that you cannot have followed me 
even in this extremely elementary exposition of 
the structural relations of animals, without seeing 
what I have been driving at all through, which is, 
to show you that, step by step, naturalists have 
come to the idea of a unity of plan, or conformity 
of construction, among animals which appeared at 
first sight to be extremely dissimilar. 
_ And here you have evidence of such a unity of 
plan among all the animals which have backbones, 
. 
