164 ANATOMY AND PHYSIOLOGY 



that insect is permeated by 1804 aeriferous tubes 

 laro-e 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 bronchise, (that is, the 

 smaller ramifications of the tracheae,) 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 antennae, 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 well exclaim, Thi 

 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 witl 

 any one organ more than another, bu,t 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 



* Kirby and Spencc's Introd. IV. 65. 



