FOOD. 101 



for that which has been consumed, and the carbonic acid gas will be con- 

 stantly accumulating. This is particularly the case in bed-rooms, and in 

 theatres, churches, and schools. 



Perhaps it is in bed-rooms that the most harm is done. These are gene- 

 rally smaller than other rooms, and they are usually kept close during the 

 whole night. The result of sleeping in such a room is very injurious. A 

 common fire, from the draught which it produces, is very serviceable in 

 ventilating rooms, but it is at best a defective means of doing so. The 

 draught which it creates generally sweeps along near the floor between the 

 door and the fire, leaving all above the level of the chimney-piece unpu- 

 ritied. Yet scarcely any other arrangement is anywhere made for the pur- 

 pose of changing the air in ordinary rooms. 



FOOD. 



The second requisite for the preservation of health is a sufficiency of 

 nutritious food. 



Organic bodies, in which are included vegetables as well as animals, are 

 constituted upon the principle of a continual waste of substance supplied 

 by continued nutrition. 



The Nutritive System of animals, from apparently the humblest of these 

 to the highest, comprehends BXldU/nMmtary tube or cavity, into which food 



i nd from which, after undergoing certain changes, it is diflfi: 

 means of smaller vessels throughout the whole structure. In the form 

 of this tube, and in the other apparatus connected with the taking of food, 

 there are, in different animals, varieties of structure, all of which are i 



y in conformity with peculiarities in the quality and amount ..f 

 i which the particular animals are designed to take. The harmony to 

 in these arrangements is remarkably significant of that Crea- 

 tive ., be traced in all thin--. 



MAN I)KSIGNED TO LIVE ON A Mi\i:i) DIET. Some animals ai 

 to live upon vegetable substances alone; others are calcu la te<l to live a] 



other animals, Herbivorous animals, as the form 'led, 



generally a long and complicated alimentary tub.-, because the nutri- 

 ich fond, bring comparatively small in proportion to the 

 whole bulk, requires '.\ givat. r -pace in which to be extracted ami . 

 into the system. The >hrcp, f..r example, has aseriesof intestines, twenty- 

 the length of its b<>dv. l-'or the oppite reasons carnivorous 



[ine tril f .|uadnipeds. and the rapa- 



lly a Short int- nner class of 



