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ANATOMY AND PHYSIOLOGY 
that insect is permeated by 1804 aeriferous tubes 
large enough to be visible, and it is probable that an 
equal number exist so small as to elude the sight, 
even when assisted by the most powerful glasses. 
“ Surprising as this number may appear, it is not 
greater than we may readily conceive to be necessary 
for communicating with so many different parts ; for, 
like the arterial and venous trees which convey and 
return the blood to and from every part of the body 
in vertebrate animals, the broncliiee, (that is, the 
smaller ramifications of the tracheee,) are not only 
carried along the intestines and spinal marrow, each 
ganglion of which they penetrate and fill, but they 
are distributed also to the skin and every organ of the 
body, entering and traversing the legs and wings, the 
eyes, the antennm, and palpi, and accompanying the 
most minute nerves through their whole course. How 
essential to the existence of the animal must the 
element be that is thus anxiously conveyed, by a 
thousand channels so exquisitely formed, to every 
minute part and portion of it ! Upon considering 
this wonderful apparatus, we may w ell exclaim. This 
hath God wrought, and this is the work of his hands” 
Adipose tissue, and Secretions . Although the 
former of these is not in immediate connection with 
any one organ more than another, but fills the 
splachnic cavity wherever it is not occupied by other 
substances ; yet it so far bears a relation to the func- 
tion of digestion and the nutritive organs, that it 
Kirby and Spence’s Introd. IV. 65. 
