



DIVISIONS OF THE ANIMAL KINGDOM. XXIX 



ing part of the canal, termed the intestines, which consist 

 of a tube of prodigious length, convoluted and packed within 

 the abdomen. The chyme, as it passes onward, mixes with 

 other fluids secreted from the liver and other organs, and is 

 separated into two portions, one of which, termed Chyle, is 

 to form the matter of nutrition to the body, and the other to 

 be excreted at the termination of the intestinal canal. Com- 

 municating with this canal is a vast system of vessels, termed 

 absorbents, which drink up, or absorb, the matter of the chyle, 

 and which, gradually uniting into larger branches, carry on- 

 ward the matter of the chyle, and at length uniting, pour it 

 into veins which are carrying the blood to the heart, and 

 thus mingle the nutrient matter of the aliment with the blood. 

 The blood, carried to every part of the system in myriads of 

 vessels, gives off the various matters which form the tissues 

 of the body, as the matter of muscle or flesh, where that is 

 required to be formed, bone, where bone is to be deposited, 

 nerve, fat, and all the other matters which form the animal 

 substance. 



In all the vertebrata, the sexes exist in distinct indivi- 

 duals. The female has one or more organs from which the 

 ova, which contain the germ of the young, are detached after 

 conception. In the greater number of tribes, fecundation 

 takes place before the ovum leaves the body ; in certain rep- 

 tiles, and in most fishes, impregnation takes place after the 

 exit of the ovum. 



The vertebrata, it has been seen, are divided into four 

 groups ; each distinguished by peculiarities of organization, 

 but all conforming to a common type. The simplest are 

 Fishes, the next Reptiles, the next Birds, the last, and most 

 perfectly developed in their organs, Mammalia. 



Fishes have organs suited to the liquid medium which they 

 inhabit. They breathe by means of gills ; and have but 

 the rudiments of lungs, which are presented in the form of 

 simple air-sacs. Their bones are more soft and cartilaginous 

 than in the orders above them. Their limbs are short and 



