ALIMENTATION. 171 



the toxic influence, the temperature of the body is lowered, and an animal will live in 

 aa atmosphere which will produce instantaneous death in one that is fresh and vigorous. 

 Bernard has made a number of curious and instructive experiments on this point. In 

 one of them a sparrow was confined under a bell-glass for one hour and a half, at the 

 end of which time another was introduced, the first being still quite vigorous. The second 

 became instantly much distressed and died in five minutes; but, ten minutes after, the 

 sparrow which had been confined for more than an hour and a half was released and flew 

 away. The points to which we have alluded have been confirmed and the observations 

 somewhat extended by the more recent researches of Bert. This is simply demonstrating, 

 with experimental accuracy, a fact of which we are all conscious; for it is well known 

 that, going from the fresh air into a close room, we experience a malaise which is not 

 felt by those who have been in the room for a length of time and whose emanations have 

 vitiated the atmosphere. 



CHAPTER VI. 



ALIMENTATION. 



Appetite Circumstances which modify the appetite Influence of habit Hunger Seat of the sense of hunger- 

 Thirst Seat of the sense of thiret Duration of life in inanition Division of alimentary principles Nitrogen- 

 ized alimentary principles Non-nitrogenized alimentary principles Inorganic alimentary principles Water 

 Alcohol Distilled liquors Wines, malt liquors, etc. Coffee Tea Chocolate Condiments and flavoring articles 

 Quantity and variety of food necessary to nutrition Necessity of a varied diet. 



IN the organism of animals, every part is continually undergoing what may be called 

 physiological decay ; the organic nitrogenized principles are being constantly transformed 

 into effete matter; and, as these constituents never exist without inorganic principles, with 

 which they are closely and inseparably united, it is found that the products of their decay 

 are always discharged from the body in combination with inorganic matters. This pro- 

 cess of molecular change is a necessary and an inevitable condition of life. Its activity may 

 be increased or retarded by various means, but it cannot be arrested. The excremen- 

 titious principles which are thus formed are produced constantly by the tissues and must 

 be continually removed from the organism, otherwise they accumulate and induce serious 

 toxic conditions. Examples of this are found in those diseases of the kidneys which in- 

 terfere with the elimination of urea, producing ura3mic poisoning, and in diseases of the 

 liver which interfere with the elimination of cholesterine, giving rise to cholesteraemia. 



It is evident, from the amount of matter that is daily discharged from the body, 

 that the process of disassimilation, as it is called, must be very active. Its constant 

 operation necessitates a constant appropriation of new matter by the parts, in order that 

 they may maintain their integrity of composition and be always ready to perform their 

 functions in the economy. The blood contains all the principles necessary for the regen- 

 eration of the organism. Its inorganic constituents are generally found in the form in 

 which they exist in the substance of the tissues ; but the organic principles of the parts 

 are formed in the substance of the tissues themselves, by a transformation of material 

 furnished by the blood. The physiological decay of the organism is, therefore, being 

 constantly repaired by the blood ; but, in order to keep the great nutritive fluid from 

 becoming impoverished, the materials which it is constantly losing must be supplied from 

 some source out of the body, and this necessitates the ingestion of matters which are 

 known as food. Food is taken into the body in obedience to a want on the part of the 

 system, which is expressed by the sensation of hunger, when it relates to solid or semi- 

 solid matters, and thirst, when it relates to water. As these sensations constitute the 

 first cause of the introduction of materials capable of regenerating the blood, their 



