ns 



ON THE DIGESTIVE FUNCTION, ETC. 



at the rate of eighty miles an hour through its void regions ; he should yet 

 allow himself to be the mere sport of the whirlwind, and not tame to his 

 use, and harness to his car, the winged strength of these aerial racers, and 

 thus stamp with reality some of the boldest fictions of the heathen poets ? 

 The hint has indeed long been thrown out ; and the perfection to which 

 the art of falconry was carried in former times, sufficiently secures it 

 against the charge of absurdity or extravagance. 



LECTURE XII. 



ON THE DIGESTIVE FUNCTION AND THE ORGANS CONTRIBUTORY TO IT ; 

 THE DIFFERENT KINDS OF FOOD EMPLOYKD BY DIFFERENT ANIMALS; 

 CONTINUANCE OF LIFE THROUGH LONG PERIODS OF FASTING. 



Under every visible form and modification matter is perpetually chan- 

 ging : — not necessarily so, or from its intrinsic nature ; for the best schools 

 of ancient times concur with the best schools of modern times, in holding 

 its elementary principles, as I have already observed, to be soUd and un- 

 changeable ; and we have still further seen, that, even in some of its com- 

 pound, but gaseous, etherealized, and invisible forms, it is probably alike 

 exempted from the Jaw of change ; while the Christian looks forward with 

 holy hope to a period when this exemption will be general, and extend to 

 every part and to every compound ; to a period in which there will be new 

 heavens and a new earth, and what is now corrup-tible will put on incor- 

 ruption. 



At present, however, we can only contemplate matter, under every visi- 

 ble form and modification, as perpetually changing ; as living, dying, and 

 reviving ; decomposing into its primordial elements, and recombininginto 

 new forms, and energies, and modes of existence. The germ becomes a 

 seed, the seed a sapling, the sapling a tree : the embryo becomes an infant, 

 the infant a youth, the youth a man ; and having thus ascended the scale 

 of maturity, both instantly begin the downward path to decay ; and, so far 

 as relates to the visible materials of which they consist, both at length 

 moulder into one common elementary mass, and furnish fresh fuel for fresh 

 generations of animal or vegetable existence. So that all is in motion, all 

 is striving to burst the bonds of its present state ; not an atom is idle ; and 

 the frugal economy of nature makes one set of materials answer the pur- 

 pose of many, and moulds it into every diversified figure of being, and 

 beauty, and happiness. 



But till the allotted time of existence has arrived, animals and vegeta- 

 bles are rendered equally capable of counteracting the waste they are per- 

 petually sustaining in their individual frames : and are wisely and benevo- 

 lently endovved with organs, whose immediate function it is to prepare a 

 supply of reformative and vital matter adequate to the general demand. 



Of this class of organs in plants we took a brief survey in our eighth lec- 

 ture ; and shall now proceed to notice the same class as it exists in animals, 

 and which is generally distinguished by the name of the digestive system. 



There is, perhaps, no animal function that displays a larger diversity of 

 means by which it is performed than the present : and, perhaps, the only 

 point in which all animals agree is in the possession of an internal canal or 



