3 76 Mr. Hunter’s ObfervatJons on the 
In my account I (hall pay fome attention to the relations of 
men who have given facts without knowing their caufes, when- 
ever I find that luch facts can be explained upon true principles 
of’ the animal ceconomv, but no further. 
This order of animals has nothing peculiar to fifh, except 
living in the fame element, and being endowed wdth the 
fame powers of prog refit ve motion as thofe fifli that are 
intended to move with a confiderable velocity : for I be- 
lieve, that all that come to the furface of the water (which 
this order of animals mud do) have confiderable progrefiive 
motion ; and this reafoning we may apply to birds ; for thofe 
which foar very high have, the greatefi: progrefiive motion. 
Although inhabitants of the waters, they belong to the: 
fame clafis as quadrupeds, breathing air, being furnifhed with 
lungs, and all the other parts peculiar to the oeconomy of that 
clals, and having warm blood ; for we may make this general 
remark, that in the different clafles of animals there is never 
any mixture of thofe parts which are eflential to life, nor in 
their different modes of fenfation. 
I fhall divide what is called the oeconomy of an animal, 
firft, into thofe parts and actions which refpect its internal 
fundtions, and on which life immediately depends, as growth, 
wafte, repair, fhifting or changing of parts, &c. the organs 
of refpiration and fecretion, in which we may include the 
powers of propagating the lpecies. 
Secondly, into thole parts and adtions which refpedt external 
objedts, and which are varioufly conftrudted, according to 
the kind of matter with which they are to be connected, 
whence they vary more than thofe of the firft divifion. 
Thefe are the parts for progrefiive motion, the organs of fenfe 
and 
