18 DIFFERENCES BETWEEN ANIMALS AND PLANTS. 



53. The well-defined and compact forms of the organs 

 lodged in these cavities, is also another peculiarity of ani- 

 mals. In plants, the organs designed for special purposes 

 are not embodied into one mass, but are distributed over 

 various parts of the individual. Thus, the leaves, which 

 answer to the lungs, instead of being condensed into one 

 organ, are scattered in countless numbers over the branches. 

 Nor is there any one organ corresponding to the brain, the 

 heart, the liver, or the stomach. 



54. Moreover, the presence of a proper digestive cavity, 

 involves marked differences between the two kingdoms, in 

 respect to alimentation or the use of food. In plants, the 

 fluids absorbed by the roots are carried, through the trunk 

 and all the branches, to the whole plant, before they arrive 

 at the leaves, where they are to be digested. In animals, 

 on the contrary, the food is at once received into the digest- 

 ive cavity, where it is elaborated ; and it is only after it has 

 been thus dissolved and prepared, that it is introduced into 

 the other parts of the body. 



55. Plants commence their development from a single 

 point, the seed, and, in like manner, all animals are deve- 

 loped from the egg. But the animal germ is the result of 

 successive transformations of the yolk, while nothing similar 

 takes place in the plant. The subsequent development of 

 individuals is also different in the two kingdoms. No limit 

 is placed to the increase of plants ; trees put out new 

 branches and new roots as long as they live. Animals, on 

 the contrary, have all a limited size and figure ; and these 

 once attained, the subsequent changes are accomplished 

 without any increase of volume or essential alteration of 

 form ; while the appearance of vegetables is frequently 

 modified, in a notable manner, by the development of new 

 branches. 



56. In the effects they produce upon the air, by respira- 



