iv. 4— iv. 5. 97 



we shall have to deal specially with generation and development 

 hereafter, it will be more convenient to defer the consideration 

 of these parts to that occasion. 



(Ch. <f.) Very different from the animals we have as yet con- 

 sidered are the Cephalopods, and the Crustacea. For these have 

 absolutely no viscera ^ whatsoever ; as indeed is the case with all 

 ex-sanguineous animals, in which are included two other genera, 

 namely the Testacea and the Insects. For in none of them does 

 the material out of which viscera are formed exist. None of 

 them, that is, have blood. The cause of this lies in their essential 

 constitution. For the presence of blood in some animals, its 

 absence from others, will be included in the conception which 

 determines their respective essences.^ Moreover, in the animals 

 we are now considering, none of those final causes will be found 

 to exist, which, in sanguineous animals, determine the presence 

 of viscera. For ' they have no blood-vessels nor urinary bladder, 

 nor do they breathe. All, in fact, that it is necessary for them 

 to have is some organ which shall be analogous to a heart ; for 

 in all animals there must be some central and commanding part 

 of the body, to lodge the sensory portion of the soul and the 

 source of life. They must of course also all have the organs of 

 nutrition ; and a diversity of character exists among them, 

 depending on differences of these receptacles of food. 



In the Cephalopods there are two teeth,* enclosing what is called 

 the mouth ; and inside this mouth is a fleshy substance, which 

 represents a tongue and serves for the discrimination of pleasant 

 and unpleasant food. The Crustacea have teeth corresponding to 

 those of the Cephalopods, namely their anterior teeth,^ and also 

 have the fleshy representative of a tongue. This latter part is 

 found, moreover, in all Testacea,^ and serves, as in sanguineous 

 animals, for gustatory sensations. Similarly provided also are the 

 Insects. For some of these, such as the Bees and the Flies, have, 

 as already described, a proboscis protruding from the mouth;''' 

 while others, that have no such piercing instrument in front, 

 have a part which acts as a tongue inside the mbuth.^ Such for 

 instance is the case in the Ants and the like. As for teeth, some 

 insects have them, the Bees and the Flies for instance, though 

 in a somewhat modified form, while others, that live on fluid 

 nutriment, are without them. For in many insects the teeth are 

 not organs of mastication, but weapons of defence. 



678b. 7 



