THE EVOLUTION OF ORGANIC FORM. 83 



Fertilization of the flowers is provided for in a similar manner. 

 The flowers can not reach each other, and therefore enlist insects in 

 their aid, preparing a store of food highly palatable to these air rovers, 

 and thus having their fertilizing germs carried from flower to flower. 



Such are the general agencies at work in plant-life, and producing 

 its typical form. And thus, while protecting their vital organs by a 

 rigid armor, plants provide for reproduction by adapting a portion of 

 their bodies for animal food ; gaining in this manner for their offspring 

 the powers of motion which they lack themselves. 



Yet all plants are not confined to this typical form, as all plants are 

 not confined to purely inorganic aliment. Some subsist on partly or 

 fully elaborated organic food, and these deviate from the plant and 

 approach some of the animal types of form, which we have next to 

 consider. 



In animal life very different requirements from those presented by 

 plants are exhibited, and the forms are essentially different. Yet their 

 main functions are the same. All organisms are adapted to the two 

 general purposes of food-getting and defense, to which all their other 

 powers are subordinate. 



As vegetables subsist on mineral, so animals subsist on organic 

 food, either vegetable or animal. And this food presents another es- 

 sential difference from that of plants. It exists only in the solid state, 

 while that of plants is wholly fluid. It can not be taken by direct 

 imbibition, like that of vegetables, but must be first rendered liquid 

 through some digestive process, and afterward imbibed. Thus an 

 internal stomach is necessary to all but the very lowest animals, and 

 even these improvise temporary stomachs, which foreshadow the per- 

 manent stomach. 



The animal not being bathed in an ocean of food, which it has but 

 to drink in at a multitude of mouths covering its whole periphery, as 

 in the plant must have means of drawing food to it, or organs ena- 

 bling it to go in search of food. In short, it must have motive powers. 



And for those creatures which are obliged to go in search of their 

 food, it is equally requisite that they should be able to discover its 

 locality. Sensory organs, therefore, become necessary. Consequently, 

 the animal is superior to the plant through this possession of muscular 

 and sense organs. It is also superior in being able to employ the 

 energy derived from its food, not in the building up of chemical com- 

 pounds, but in the force of motion and sensation. 



Nor can the animal be wholly protected by armor. Some portion 

 of it must be exposed to danger. At least those flexible limbs which 

 aid it in food-getting are in frequent peril, and need some form of pro- 

 tection. The loss of them can not well be made useful to the animal, 

 as the loss of its exposed portions is to the plants. 



Evidently the animal is capable of a much wider range of form- 

 evolution than the plant. In its mobility of variation it has branched 



