INTRODUCTION. 3 



The word //^ver/, which, in the Latin language, from whence 

 it was derived, means cut into or notched, was designed to 

 express one of the chief characters of this group of animals, 

 whose body is marked by several cross-lines or incisions. The 

 parts between these cross-lines are called segments, or rings, 

 and consist of a iiuiiiber of jointed pieces, more or less moval:)lc 

 on each other. 



Insects have a very small brain, and, instead of a spinal 

 marrow, a kind of knotted cord, extending from the brain to 

 the hinder extremity ; and numerous siuall whitish tiireads, 

 which are the nerves, spread from the brain and knots, in 

 various directions. Two long air-pipes, within their bodies, 

 together with an immense number of smaller pipes, supply the 

 want of lungs, and carry the air to every part. Insects do not 

 breathe through their mouths, but through little holes, called 

 spiracles, generally nine in number, along each side of the 

 body. Some, however, have the breathing-holes placed in the 

 hinder extremity, and a few young water-insects breathe by 

 means of gills. The heart is a long tube, lying under the skin 

 of the back, having little holes on each side for the admission 

 of the juices of the body, which are prevented from escaping 

 again by valves or clappers, formed to close the holes within. 

 Moreover, this tubular heart is divided into several chambers, 

 by transverse partitions, in each of which there is a hole shut 

 by a valve, w^hich allows the blood to flow only from the hinder 

 to the fore part of the heart, and prevents it from passing in 

 the contrary direction. The blood, which is a colorless or yel- 

 lowish fluid, does not circulate in proper arteries and veins ; 

 but is driven from the fore part of the heart into the head, and 

 thence escapes into the body, where it is mingled with the 

 nutritive juices that filter through the sides of the intestines, 

 and the mingled fluid penetrates the crevices among the flesh 

 and other internal parts, flowing along the sides of the air- 

 pipes, whereby it receives from the air that influence which 

 renders it fitted to nourish the frame and maintain life. 



Insects are never spontaneously generated from putrid animal 

 or vegetable matter, but are produced from eggs. A few, such 

 as some plant-lice, do not lay their eggs, but retain them within 



