122 THE FARMER AT HOM3 



made of an old spade handle, having the lower part sharpened, and 

 sometimes shod with iron. The depth of its insertion in the soil may 

 be regulated by a small cross-bar, which can be placed at various 

 heights, according to the size of the root for which it is used. In 

 some parts of England various kinds of seed are planted with a 

 dibbler. 



DIGESTION. By the term digestion, in the more perfect ani- 

 mal, is generally understood that process by which certain substances, 

 called nutritive, are converted into a homogeneous semi-fluid mass, 

 from the cavity containing which small vessels drink up the more 

 elaborated portion, and convey it into other larger ones, containing 

 blood, with which it is mixed and carried to the heart. The simplest 

 kind of digestion is that performed by presenting a watery fluid to a 

 moist surface, which converts it into its own nature. Examples of 

 this are seen in the lower orders of animals, the individuals of which 

 consist almost entirely of a closed sack or pouch, on the external sur- 

 face of which the above change is accomplished. On nearly the same 

 line may be put the spongy extremities of the roots of plants, which 

 absorb or drink up the nutrimental fluid from the soil. 



In proportion as the animal structure becomes more complex, the 

 subsidiary or preparatory organs are increased in number, to qualify 

 the stomach for acting on the great variety of food, often of a solid 

 and dense texture, which is taken for the purpose of nourishment. 

 The most generally distributed apparatus for the breaking down and 

 grinding the food, before its reception into the stomach, is the teeth. 

 In an omniverous animal, such as man, who appropriates to the 

 gratification of his appetite, food from all the kingdoms of nature, 

 these instruments are of three kinds ; the two chief, however, are the 

 front or incisor teeth, which tear, and the back or molar teeth, which 

 triturate and more minutely divide the alimentary matter, in what is 

 called mastication. In many birds, which swallow directly their food 

 without chewing or masticating, there is a mechanical contrivance, 

 in the gizzard, by which it is broken down and prepared to be, oper- 

 ated on by the stomach proper. 



Those animals, such as the serpent tribe, which swallow their 

 prey without any preliminary process, except breaking the more 

 prominent and resisting parts, such as the bones of the creatures 

 which they have seized, have very slow digestion. They will remain 

 for many hours in a half torpid state, unable and unwilling to move, 

 until the substance which they swallowed has undergone the requisite 

 change, by the digestive action of the inner surface of their stomach. 

 It would seem then to be an established principle in the history of 

 digestion, that unless the nutrimental natter be of the very simplest 

 kind, and presented in a fluid state, as in the lowest animals, and in 

 vegetables, it requires to be subjected to some preparatory process, 

 before it can be received by the stomach, and undergo in it the 



