Nov. 11, 1881.] 



* KNOWLEDGE 



23 



times of disturbance, and other regions where alternations 

 of activity are the only evidence of connection. Thus the 

 1' -vuvian and Chilian volcanic regions have seldom, if ever, 

 1 M ,11 simultaneously disturbed. A long period of disturbance 

 in the Peruvian region, culminating in the terrible earth- 

 c|uake of Riobamba, was followed by a series of disturbances 

 in the Chilian region, resulting in a permanent elevation of 

 the whole line of coast. Then came disturbances in the 

 Peruvian Andes, including the tremendous earthquake of 

 the year 1868, which so shook the shores of Peru, that the 

 sea wave then generated swept] right athwart the Pacific to 

 the shores of New Zealand, Australia, and the Asiatic con- 

 tinent. It is noteworthy that between the Chilian and 

 Peruvian regions of disturbance there is a space in which 

 no volcanic action has ever been observed ; precisely as 

 between the oscillating ends of a balance there is a region 

 of comparative quiescence. 



It certainly does not seem probable that these signs of 

 disturbance in dift'erent parts of the South European 

 volcanic region which have followed or accompanied the 

 eruption of Vesuvius have lieen free from all connection 

 ^^^th the activity of the great Sicilian vent. Certainly 

 earthquakes in SicUy have been associated with the cessa- 

 tion of the outflow of lava from Etna. Nor can there be 

 much doubt that signs of activity shown by Vesuvius after 

 Etna has been in eruption, and vice versd, indicate sym- 

 pathy between the Neapolitan and Sicilian volcanic regions. 

 It may seem extravagant to associate earthquakes in France 

 or in the British Isles with the activity of the Italian 

 volcanoes ; but there are many reasons for believing that 

 such slight eartliquakes as do from time to time occur in 

 these more northerly regions depend indirectly on the con- 

 dition of the South European region of subterranean 

 activity. It is certain that shortly before the great out- 

 burst of Vesuvius in 1868, an earthquake'more marked in 

 character than usual in this country shook the western 

 parts of England. It is well kno%vn, too, that when 

 another part of the great southern region of disturbance 

 was aSected, and Lisbon was laid in ruins, the lakes, rivers, 

 and springs of England were disturbed in a remarkable 

 manner ; the water of Loch Lomond, for instance, suddenly 

 rose, without apparent cause, against its banks, and then 

 quickly subsided to its usual level 



THE RELATION OF FOOD TO 

 MUSCULAR WORK. 



Br Dr. W. B. Carpenter, F.RS. 

 PAET II. 



IT has been shown that whilst Liebig regarded the pro- 

 duction of Muscular Energy as an expenditure of the 

 " vital force " of the muscle-substance itself — involving its 

 death and chemical transformation, and requiring nitro- 

 genous or tissue-food for its regeneration — Mayer 

 attributed the production of that energy to the oxidation 

 of a portion of the non-nitrogenous or respiratory food, 

 regarding the muscular apparatus as the mere instrument 

 by which that oxidation is made to produce Motion in 

 place of Heat. 



I shall now give a general account of the experi- 

 mental inquiries by which Liebig's doctrine has been 

 disproved and that of Mayer established. These have 

 reference to the relation of the amount of work done 

 by the body as a whole, — (1) to the relative consump- 

 tion of the nitrogenous and the non-nitrogenous com- 

 ponents of the food ; (2) to the amount of Carbonic acid 

 exhaled; and (3) to the amount of Urea passed off: — 



whUe (t) another set of experiments upon isolated muscles 

 has demonstrated the dependence of tlic production of 

 energy upon a change in the substance of the muscle itself, 

 rather than (as Mayer supposed) in the blood passing 

 through it 



1. If a man be carefully "dieted " for a time long enough 

 to determine the amount of nitrogenous aliment adequate 

 to repair the ordinary daily "waste "of his tissues, and 

 the amount of non-nitrogenous aliment needed to maintain 

 the heat of his body at its normal standard and keep liim 

 in healthful exercise, so that his weight remains the same 

 at the end of the experiment as at the beginning — and he 

 is then set to make a great addition to his daily exercise in 

 the shape of walking, pumping, turning a machine, or the 

 like — it is found that his body can be kept up to this extra 

 work by an increase in tlu; supply of non-nitrogenous 

 aliment, with such a small addition to the nitrogenous as 

 may suffice to make good the loss produced by the increased 

 " wear and tear " of the machine itself. 



2. All observations concur in showing an immediate 

 increase in the exhalation of Carbonic acid, capable of being 

 determined with rigorous exactness, when the body, pre- 

 viously at rest, is put into motion. The late Dr. Edward 

 Smith made himself the subject of a long-continued and 

 diversified series of researches upon this point, by the use 

 of a portable gas-meter, through which he could breathe 

 when walking or working at a tread-wheel, as w ell as when 

 standing still, sitting, or lying : and he found not only that 

 when continually " getting up stairs " on the tread-wheel 

 he exhaled more carbonic acid than when walking, that 

 when walking fast up-hill he exhaled more than when 

 walking slowly on level ground, and that in the latter case 

 he exlialed more than when standing still ; but that he 

 exhaled more when standing than when sitting, and more 

 when sitting upright (without support to the back) than 

 wlien lying so fully supported as not to put forth any mus;- 

 cular effort. Further, he found that when, in walking, he 

 carried a weight even of a few pounds, the exhalation of 

 carbonic acid was sensibly augmented ; the increase being 

 still greater when the weight had to be raised (a.% in walking 

 up hill), as well as transported. These results have been 

 confirmed by numerous other experimenters. They are in 

 remarkable harmony with those long pre\iously obtained 

 by Mr. Newport, upon the relative amounts of carbonic 

 acid exhaled by a bee at rest, and a bee " buzzing " under 

 a glass. 



3. The employment of more exact methods for the 

 quantitative determination of Urea than that used by 

 Liebig, has sho^^^l that he was altogether wrong in assert- 

 ing that a corresponding increase is produced by muscular 

 exertion in the (juantity of that substance eliminated by 

 the kidneys. An experiment which has now become 

 " classical " was performed upon themselves by Professors 

 Fick and Weslicenus in 1866; namely the determination 

 of the respective quantities of urea eliminated by each of 

 them for twelve hours be/ore, for eight hours duririg, and 

 for six hours after the ascent of the Faulhorn, whose 

 height is about 6,500 feet. They took no nitrogenous 

 food either for seventeen hours before the ascent, during 

 the eight hours of the ascent, or for six hours after the 

 ascent ; but then took a good ordinary meal. The mean 

 of the two determinations (between which there was a very 

 close correspondence) gave for the twelve hours before the 

 ascent, 062 gramme, being at the rate of 0052 gramme 

 per hour ; for the eight hours of the ascent 0-10 gramme, 

 or at the rate of 0'05 gramme per hour ; and the same 

 amount for the six hours following the ascent, being at the 

 rate of 0066 gramme per hour ; while for the twelve 

 hours after the subsequent meal, the mean amount was 



