May 28, 1874] 



NA rURE 



61 



and, by oxidation, to force-production." The great ques- 

 tion of the relation of nitrogenised and non-nitrogenised 

 matter to external body-work performed is entered into 

 in considerable detail, and the imp:>rtant experiments of 

 Fick and Wislicinus, Parkes, and Austin Flint, are de- 

 scribed in full ; to them being added others, performed 

 by Mr. Mahomed in the author's laboratory, on the length 

 of time required for the elimination of the products of 

 metamorphosis of an increased amount of nitrogenised 

 food, from which it may be inferred that urea is produced 

 and eliminated within the three hours following the inges- 

 tion of the nitrogenised matter. 



It is shown that the original theory of Liebig, in which 

 it is assumed that muscular action involves the destruc- 

 tion of muscular tissue, which till lately has been so 

 generally accepted, " although, in reality, constituting a 

 speculative proposition, unsupported by anything of the 

 nature of proof," is opposed to all the results of recent 

 investigation, and that if it were true " we should have to 

 look upon nitrogenous alimentary matter as forming 

 through the medium of muscular tissue, the source, and 

 the only source, of muscular power. The renewal of 

 muscular tissue for subsequent oxidation in its turn, and 

 evolution of muscular force, would thus constitute one of 

 the functions of nitrogenous alimentary matter ; and on 

 its supply would accordingly depend our capacity for the 

 performance of muscular work." Great stress is laid on 

 the necessity for the combination of nitrogenised with non- 

 nitrogenised food for the sustenance of the body in a 

 vigorous condition; and Mr. Savory's experiments on this 

 point are shown to be quite insufficient to prove the in- 

 ference which has been frequently drawn from them, 

 namely, that nitrogenous matter, combined only with the 

 appropriate saline principles, suffices for the maintenance 

 of life. 



The author reduces the unnecessarily extensive lite- 

 rature on the action of alcohol, which is so very negative 

 in character, into a very moderate space, remarking that 

 " from a review of the evidence as it at present stands, it 

 may reasonably be inferred that there is sufficient before 

 us to justify the conclusion that the main portion of the 

 alcohol ingested becomes destroyed within the system ; 

 and if this be the case, it may be fairly assumed that the 

 destruction is attended with oxidation and a corresponding 

 liberation of force, unless, indeed, it should undergo meta- 

 morphosis into a principle to be temporarily retained, but 

 nevertheless ultimately applied to force-production. The 

 subject appears to me to be open to physiological as well 

 as chemical investigation, and probably some additional 

 light may be hereafter thrown upon it by an approach 

 through the former channel." 



The discussion of the sources of each of the different 

 most important articles of diet is followed by a concise 

 account of its practical value. In the present time of 

 excessive tea-drinking, the following description of the 

 action of tea is of particular interest. " To express in a 

 few words the advantages derivable from the use of tea, 

 it may be said that it forms an agreeable, refreshing, and 

 wholesome beverage, and thereby constitutes a useful me- 

 dium for the introduction of a portion of the fluid we 

 require into the system. It secures that the water con- 

 sumed is safe for drinking by the boiling which is neces- 

 sitated as a preliminary operation in making tea. It cools 



the bo ly when hot, probably by promoting the action of 

 the skin ; and warms it when cold, by virtue, it would 

 seem, of the warm liquid consumed. In a negative 

 way it may prove beneficial to health by taking the 

 place of a less wholesome liquid. Through the milk 

 and sugar usually consumed with it in England, it affords 

 the means of applying a certain amount, and not by any 

 means an insignificant amount, viewed in its entirety, of 

 alimentary matter to the system. E.xpenence shows that 

 it often affords comfort and relief to persons suffering from 

 nervous headache. It also tends to allay the excitement 

 from, and counteract the state induced by, the use of 

 alcoholic stimulants ; and further, on account of its anti- 

 soporific properties, like coffee, it is useful as an antidote 

 in poisoning by opium." 



Besides the important purely physiological problems 

 that are entered into in the work before us, there 

 are so many which have a strictly practical bearing, and 

 they are treated in so clear and impressive a manner, that 

 the ordinary reader cannot but feel that he has derived 

 great benefit from a careful study of its contents. Much 

 stress is laid in the chapter on Practical Dietetics on the 

 importance of a midday meal : — " A fairly substantial 

 meal should be taken at this time, and it does not signify 

 whether it goes under ths name of luncheon or dmner." 

 Carnivorous animals apparently thrive best when fed at 

 long intervals ; herbivorous, when they are constantly 

 eating. Man being omnivorous, his food should be taken 

 at intervals of much less duration than the carnivora, and 

 therefore in diminished quantities at each, three fairly 

 substantial meals during the day, at intervals of five or 

 six hours being found the best in the long run- " There 

 are many business or professional men who, after leaving 

 home for their office or chambers in the morning, do not 

 taste food, or, if they do, take only a minute quantity, until 

 they return in the evening. Actively engaged all day, 

 their system becomes exhausted, and they arrive home in 

 a thoroughly jaded or worn-out condition. They expect 

 that their dinner is to revive them. It may do so for a 

 wliile, but it is only a cjuestion of time how long this 

 system can be carried on before evil consequences arise." 

 It is therefore stated as a sine qua non that the interval 

 between breakfast and late dinner should be broken by a 

 repast about half-way between them. 



LETTERS TO THE EDITOR 



[The Editor docs not hold himself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous 

 communications .] 



Physical Axioms 



Mr. Collier's letter demands from me a reply, which I will 

 endeavour to make as brief as possible. 



Mr. Silencer, instead of answering the difficulties which I had 

 shown las i /;w;7 view of the Second Law of Motion to involve, 

 o'lly noticed my remarks to dismiss them summarily with the 

 lofty sentence that I "proposed to exemplify unconsciously- 

 formed preconceptions," and had commitled an absurd blunder 

 in Si) cluing. And now, because it did not appear to me worth 

 while, at the expense of your space and your readers' patience, 

 explicitly to repudiate any such lofcy purpose, and so, adopting 

 Mr. Spencer's words, I merely called attention to the fact that 

 the example (of whatever it might be considered to be an exem- 

 plification) was of Mr. Spencer's own choosing, I am charged 

 by Mr. Spencer's follower, Mr, Collier, with having " confused 

 issues," which I neither raised nor accepted. If Mr. Collier will 



