NATURE AND DESTINATION OF FOOD. 119 



/ 



cold, as well as other depressing agencies, is diminished rather than increased 

 by their habitual employment; and the reason Of this, so far as cold is con- 

 cerned, is sufficiently obvious. Under ordinary circumstances of exposure 

 to cold the circulation of blood through the vessels of the surface, owing to 

 the contraction of the cutaneous capillaries, is greatly reduced, and much 

 less heat is lost by conduction and radiation, the skin alone being a very had 

 conductor. 1 When, however, considerable quantities of Alcohol are taken, 

 more or less complete paralysis of the vaso-motor nervous system is the re- 

 sult : the vessels of the skin no longer respond to the stimulus of cold, and 

 the blood traversing them loses a large amount of heat ; so that whilst in 

 all instances where the quantity of Alcohol consumed exceeds the moderate 

 limits of 1^-2 ounces per diem, there is diminished power of resistance to 

 cold, this is felt much more acutely in extreme cases, and death may even 

 take place from the general reduction of the temperature. 2 On these 

 grounds, the Author has felt himself fully justified in the conclusion, that, 

 for Physiological reasons alone, habitual abstinence from Alcoholic liquors 

 is the best rule that can be laid down for the great majority of healthy in- 

 dividuals ; the exceptional cases in which any real benefit can be derived 

 from their use being comparatively few. 3 . 



73. The very extensive employment of Tobacco by men of almost every 

 rank in society in this country, and the large consumption of Tea and Coffee 

 by both sexes throughout the community, render the study of their effects 

 upon the animal economy particularly interesting, though up to the present 

 time exceedingly few observations have been made. The effects of Tobacco 

 are chiefly due to the absorption of the extremely poisonous liquid alkaloid 

 Nicotia, 4 which exists in the plant in combination with Citric and Malic 

 acids, and from its remarkable volatility, is contained in and inhaled with 

 the smoke of the smouldering leaves. Its chemical composition is repre- 

 sented by .the formula C 10 H 14 N,. Dr. Hammond's conclusions (Op. cit ) from, 

 his experiments upon the use of Tobacco are, that whilst it only slightly 

 affects the excretion of carbonic acid from the lungs, it diminishes the 

 quantity of fteces, urine, aqueous vapor, and of chlorine, but it increases the 

 amount of uric, phosphoric, and sulphuric acids eliminated by the kidneys, 

 circumstances which seem to indicate that there is an increase in the inter- 

 stitial changes taking place in the brain and nervous tissue, of which there 

 are other indubitable signs, as wakefulness, trembling, and nervous excite- 

 ment. The quantity employed in the experiment was two cigars thrice a 

 day. These results accord with general experience ; and there are few who 

 will not coincide with the moderate tone of Sir B. Brodie's well-known letter 

 to the Times on this subject, dated August 27th, 1860, in which he observes 

 that when used in limited quantity, and under circumstances of privation, 

 Tobacco may be not only harmless but absolutely beneficial by soothing and 

 tranquillizing the nervous system, allaying hunger and the uneasy feelings 

 produced by mental and bodily exhaustion ; but that in too many instances 

 it is only a bad habit, producing a greater or less degree of derangement of 

 the nervous system, and indisposing to both mental and bodily exertion. 

 Tea and Coffee, though derived from different classes of the Vegetable king- 



1 See Kliig., Znits. f. Biologic, Band x, 1874, p. 73. 



2 A very remarkable example of the effects of cold on whisky and non-whisky 

 drinkers is recorded in the Lancet, vol. i, 1871, p. 636. 



3 S"e his Physiology of Temperance and Total Abstinence; also the important 

 Treatise on Alcoholismus Chronicus, by Dr. Huss of Stockholm, of which an ab- 

 stract is sriven in the Brit, and For. Med.-Chir. Rev., vols. vii and ix. 



4 See Heubel, Exp. Beitiiige, Centralblatt f. d. Med. Wiss., 1872, p. 641. 



