620 



SCIENCE. 



pressed in the measure of labor, have amounted to 54,6x 

 425, that is 23205 grammillimeters. 



The chemical process, which takes place in muscular 

 action is, it is true, by no means accurately known in the 

 individual stages of its course ; but as a whole, it un- 

 doubtedly consists in the combustion of a body free from 

 nitrogen, whether fatty or saccharine, to carbonic acid 

 and water. The numbers obtained, therefore, afford us 

 a point, by which to determine what quantities of the 

 above mentioned materials must be consumed in a mus- 

 cular contraction. We know, through Frankland's re- 

 searches, that in the consumption of 1 mgr. of sugar the 

 chemical powers of attraction perform as much work a 

 is necessary to produce 3800 units of heat. Now, since 

 in the ten contractions of our experiment, 54,6 units of 

 heat were produced, an expenditure of material of 5,46-=- 

 3800=0,014 mgr. would have been necessary, under the 

 supposition, that the combustible material was a saccha- 

 rine body. Let us suppose that the combustible ma- 

 terial is a fatty body, then a still smaller expenditure would 

 be sufficient, to produce the effect observed, namely, 

 54,6-^-9000=0,0067 mgr., because 1 mgr. of fat, accord- 

 ing to the estimates of the investigator just mentioned, 

 supplied in its combustion, 9000 units of heat. S07 for 

 one contraction the combustion of 0,0014 m g r - of sugar, 

 or of 0,00067 m S r - °f f at > would have been requisite. If 

 we divide this number by 3.1 (the weight of the quantity 

 of muscle used in grams) the result will show how much 

 material must be consumed at o?ie energetic contraction 

 in a gram of muscular substance, that is 0,00045 mgr. of 

 a saccharine, or 0,00022 of a fatty combination. So it ap- 

 pears, that for 1000 energetic contractions not quite 1 mgr. 

 of combustible material in each gram of muscle is 

 requisite, and, therefore, it can no longer surprise us, that 

 only very small quantities of the actual combustible ma- 

 terial are ever found in the muscular substance, the greater 

 portion of which, as is well known, really consists of very 

 different materials, principally of substances like the white 

 of an egg. 



The results obtained with the new systems can be ap- 

 plied to the decision of the question, what portion of the 

 work performed by chemical powers in the active muscle, 

 can, in the most favorable cases, produce mechanical out- 

 ward effects. The closest interest in this question might 

 be designated as an "economical" one. In fact, the 

 real object of the animal subject in muscular activity is 

 the production of mechanical effects in the surrounding 

 universe, and one might denote the portion of the work 

 accomplished by chemical powers, which is applied to the 

 mere production of heat, as an inevitable loss from the 

 point of view of animal economy. At any rate, one will 

 have the more reason to admire the judicious arrangement 

 of the muscular substance, which can apply a larger por- 

 tion of the chemical labor performed in it to external me- 

 chanical results. 



It is precisely the same as in the steam-engine, whose 

 construction we also call the more perfect, according to 

 the larger portion of the work performed by the chemical 

 powers of attraction in the burning of the coal it allows 

 to be used to produce mechanical effects. In spite of ihe 

 most eager efforts of technics hitherto no attempt has 

 been successful in making more ihan of this labor me- 

 chanically effectual. Fully f„ are lost to the objects of the 

 machine, by being inevitably emplo>ed in the production 

 of heat, which at the utmost can only be used for minor 

 purposes, such as the heating of rooms and similar ob- 

 jecis. 



If it must now be ascertained, how the muscle is situ- 

 ated in this respect, it is only nectssary to fix, by experi- 

 ment like the one above described, what mechanical ef- 

 fect has been accomplished in a given time, and compare 

 this measured in the p'oporiion of work, with the chemi- 

 cal labor calculated by the heat produced. It will be ad- 

 visable to pay special attention to the fact, that the heat 

 finally developed would be less by a corresponding 



amount, if the experiment had been so arranged, that the 

 mechanical effect, that is the raising of the weight, had 

 been maintained. The quantity of heat corresponding 

 with this effect was first released in the muscle by the fall- 

 ing of the burden again. 



By the 10 contractions of the foregoing experiment 500 

 gr. were raised on an average about 1.3 mm. high. Thus 

 the mechanical result amounted in the whole to 6,670 

 grammillimeters. The work performed by chemical pow- 

 ers of attraction in the 10 contractions we have found 

 above — 23,205 grammillimeters. This number is about 

 3^ times 6,670. Thus, by these contractions, somewhat 

 over i of the whole chemical labor was applied externally 

 and not quite J to the direct production of heat. That in 

 the actual experiment this quarter was also finally con- 

 verted into heat, depended merely on the external arrange- 

 ments, which permitted the burden raised to fall again 

 each time. 



We see by this, that — as was to be expected — the mus- 

 cle machine is very superior to even the most perfect 

 steam-engine, in so fat that it can err ploy the combustible 

 material twice as frugally for the same main object. 



Besides, this relation between mechanical action and de- 

 velopment of heat is by no means obtained at every mus- 

 cular contraction. I have intentionally selected from my 

 experiments as an example, the one in which the mechan- 

 ical labor amounts to the largest fraction of the whole 

 chemical labor. To obtain this most favorable propor- 

 tion, the burden must stand in a certain relation to the 

 thickness of the muscle. If the burden is larger or smal- 

 ler, a smaller portion of the chemical work will be used 

 for mechanical act on, or — as it might be expressed — the 

 combustible material will be less economically used. This 

 proposition may be demonstrated a priori, tor it is easily 

 seen, that in the two extreme cases, where the burden is 

 a cypher or infinitely great, chemical work is performed 

 and heat developed, but no external mechanical action is 

 obtained. 



The solution of the question, in what relation the me- 

 chanical action for the development of heat can stand, 

 under the most favorable circumstances, towards the mus- 

 cular contraction, enables an observation to be made 

 which throws new light upon the change of substance in 

 animal bodies. As is well known, the change of sub- 

 stance in animal forms may be designated in general as a 

 process of combustion. In reality, a certain quantity of 

 combustible nutritious matter daily enters into the fluids, 

 and a corresponding quaniiiy of oxygen is taken in with 

 the breath. On the other hand, every day on an average, 

 a precisely similar quantity of substances is withdrawn, 

 whose combination is to be regarded as the product of an 

 almost total combustion of the nu'ritious matter. The 

 condition of the body with this equal balance between 

 receipts and expenditures, remains for a long time appar- 

 ently unchanged. 



With the formation of the product of combustion from 

 the assimilated nutritious matter and the inhaled oxygen, 

 the colossal power of attraction of this element for the 

 elements of the nutritious matter, especially for the carbon 

 and hydrogen gas, now performs a fixed amount of labor, 

 which is independent of where the combustion takes 

 place, and whether it occurs at once or in various stages 

 at various places. 



People were formerly inclined to suppose, that the 

 greater portion of the combustion in question occurs either 

 in the fluids themselves or in special organs, such as the 

 liver, the kidneys, etc. 



Since the changes occurring in animal bodies have be- 

 gun to be viewed from the standpoint of the principle of 

 the preservation of power, it must be looked upon as a 

 self-evident truth, that at least a certain portion of the as- 

 similated nutritious matter passes into the muscles, to be 

 first consumed here, since from the point of view of that 

 principle, the mechanical performance of the muscles can 

 only be understood as the action of the labor of the 



