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572 The Harmony of Creation. 
terrestrial animals, whether of land or water, which breathe 
otherwise than by branchia, belong to the two classes 
which breathe either by trachea or lungs. Less perfect 
than pulmonary, tracheal respiration is peculiar to the class 
of insects,and some Arachnida. We find this function 
perfectly represented in the animals of the Paleozoic 
epoch. As has already been stated, Coleoptera, Orthop- 
tera, and Neuroptera, all possessing tracheal respiration, 
have been discovered in the Palseozoic strata. As the in- 
sects belong to the same, or analogous genera with those 
which now exist, we must assume that they were endowed 
with the same respiratory organs. We arrive therefore, at 
the conclusion, as well for terrestrial animals which breathe 
by trachea as for marine animals, that the respiratory 
organs have not undergone any progressive improvement, 
and that this class is now what it was in the cradle of Na- 
ture—in fine, that the medium of its terrestrial existence 
has always been the same since the first animalisation of 
the globe to the present time. The primitive genera of 
marine animals, or those most closely allied to them, which 
still represent them on the earth, prove that they had from 
the first the organic characters which they still preserve ; 
that they have undergone no gradual improvement in 
organisation ; that the medium in which they lived at the 
earliest epoch of the creation was the same as at present , 
that, therefore, no great change has taken place as to the 
conditions of vitality of these beings, and that the seas in 
which they then existed were essentially similar to those 
which they now inhabit. All considerations of the subject 
lead to the following conclusions :— 
First, if the supposition of a gradually increasing perfec- 
tion of organisation were admitted, we ought to find all 
the animals endowed with mere cutaneous respiration in 
the first stages of the world; and the others, proceeding 
successively from age to age, endowed with branchial, 
tracheal, and pulmonary respiration, whereas, on the con- 
trary, we find in the very first epoch of the animalisation of 
the globe, all the modes of respiration manifested at once 
—a conclusion entirely at variance with the supposition of 
progressively improving organisation. Secondly, whether 
we compare together the increasing or decreasing develop- 
ment of zoological forms, or the dates of the appearance of 
the orders of animals with the perfection of their organs; 
or take for the basis of our comparative researches, the 
physiological conclusion deduced from the modes of respi- 
