DEFINITION OF THE TERM INSECT. 5 
stotle distinguishes by the nature of their integument 
and its contents) in any of the other classes into which 
he divided animals without blood. It was on account of 
this most obvious of their characters, that these little 
creatures were in Greek named Entoma, and in Latin 
Insecta ; and from the former word, as you know, our 
favourite science takes the name of Entomology. 
Pliny adhering to the definition of Aristotle, as far as 
it relates to the znsection of the animals we are speaking 
of, expressly includes Apods, as well as Aptera, amongst 
them?; and in this was followed, without any attempt at 
improvement, by all the entomological writers that inter- 
vened between him and the great Aristotle of the mo- 
derns, Linné. 
This illustrious naturalist, aware of the .:acorrectness 
of the primary divisions of the animal kingdom founded 
upon the presence or absence of blood, establishes his 
system upon the structure of the heart, and upon the 
temperature and colour of the circulating fluid. He di- 
vided animals into two great sections or sub-kingdoms, 
each comprising two classes. His first section included 
those having a heart with ¢wo ventricles, ¢wo auricles, 
and warm and red blood, viz. the Mammalia or beasts, 
and the Aves or birds. His second, those having a heart 
with one ventricle, one auricle, and cold and red blood, 
namely, the classes Amphibia, which included reptiles, 
serpents, &c. and Pisces or fish. His third, those having 
a heart with one ventricle and no auricle, and cold white 
- sanies in the place of blood, namely, his classes Insecta 
and Vermes, including the Invertebrate animals of La- 
Ente Wat, ® xitec. 1. 
