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1.Humboldt, Views of Nature, Bohn’s ed., London, 1850, p. 380. This allegory did not appear in the first edition of the Views of Nature. In the preface to the second edition the author gives the following account of its origin: “Schiller,” he says, “in remembrance of his youthful medical studies, loved to converse with me, during my long stay at Jena, on physiological subjects.” * * * “It was at this period that I wrote the little allegory on Vital Force, called The Rhodian Genius. The predilection which Schiller entertained for this piece, which he admitted into his periodical, Die Horen, gave me courage to introduce it here.” It was published in Die Horen in 1795.

2.Humboldt, op. cit., p. 386. In his Aphorismi ex doctrina Physiologiæ chemicæ Plantarum, appended to his Flora Fribergensis subterranea, published in 1793, Humboldt had said “Vim internam, quæ chymicæ affinitatis vincula resolvit, atque obstat, quominus elementa corporum libere conjungantur, vitalem vocamus.” “That internal force, which dissolves the bonds of chemical affinity, and prevents the elements of bodies from freely uniting, we call vital.” But in a note to the allegory above mentioned, added to the third edition of the Views of Nature in 1849, he says: “Reflection and prolonged study in the departments of physiology and chemistry have deeply shaken my earlier belief in peculiar so-called vital forces. In the year 1797, * * * I already declared that I by no means regarded the existence of these peculiar vital forces as established.” And again: “The difficulty of satisfactorily referring the vital phenomena of the organism to physical and chemical laws depends chiefly (and almost in the same manner as the prediction of meteorological processes in the atmosphere) on the complication of the phenomena, and on the great number of the simultaneously acting forces as well as the conditions of their activity.”

3.Compare Henry Bence Jones, Croonian Lectures on Matter and Force. London, 1868, John Churchill & Sons.

4.Ib., Preface, p. vi.

5.Rankine, W. J. M., Philosophical Magazine, Feb., 1853. Also Edinburgh Philosophical Journal, July, 1855.

6.Armstrong, Sir Wm. In his address as President of the British Association for the Advancement of Science. Rep. Brit. Assoc., 1863, li.

7.Grove, W. R., in 1842. Compare “Nature” i, 335, Jan. 27, 1870. Also Appleton’s Journal, iii, 324, Mch. 19, 1870.

8.Id., in Preface to The Correlation of Physical Forces, 4th ed. Reprinted in The Correlation and Conservation of Forces, edited by E. L. Youmans, p. 7. New York, 1865, D. Appleton & Co.

9.Id., ib., Am. ed., p. 33 et seq.

10.Joule, J. P., Philosophical Transactions, 1850, p. 61.

11.See American Journal of Science, II, xxxvii, 296, 1864.

12.The work (W) done by a moving body is commonly expressed by the formula W = MV², in which M, or the mass of the body, is equal to w/2g; i.e., to the weight divided by twice the intensity of gravity. The work done by our cannon-ball then, would be (1 × (1100)²)/(2 × 64⅓) = 9,404·14 foot-tons. If, further, we assume the resisting body to be of such a character as to bring the ball to rest in moving ¼ of an inch, then the final pressure would be 9,404·14 × 12 × 4 = 451,398·7 tons. But since, “in the case of a perfectly elastic body, or of a resistance proportional to the advance of the center of gravity of the impinging body from the point at which contact first takes place, the final pressure (provided the body struck is perfectly rigid) is double what would occur were the stoppage to occur at the end of a corresponding advance against a uniform resistance,” this result must be multiplied by two; and we get (451,398·7 × 2) 902,797 tons as the crushing pressure of the ball under these conditions. Note: The author’s thanks are due to his friends Pres. F. A. P. Barnard and Mr. J. J. Skinner for suggestions on the relation of impact to statical pressure.

13.The unit of impact being that given by a body weighing one pound and moving one foot a second, the impact of such a body falling from a hight of 772 feet—the velocity acquired being 222¼ feet per second (=√(2sg))—would be 1 × (222¼)² = 49,408 units, the equivalent in impact of one heat-unit. A cannon-ball weighing 1000 lbs. and moving 1100 feet a second would have an impact of (1100)² × 1000 = 1,210,000,000 units. Dividing this by 49,408, the quotient is 24489 heat units, the equivalent of the impact. The specific heat of iron being ·1138, this amount of heat would raise the temperature of one pound of iron 215.191° F. (24,489 × ·1138) or of 1000 pounds of iron 215° F. 24489 pounds of water heated one degree, is equal to 136½ pounds, or 17 gallons U. S., heated 180 degrees; i.e., from 32° to 212° F.

14.Assuming the density of the earth to be 5·5, its weight would be 6,500,000,000,000,000,000,000 tons, and its impact—by the formula given above—would be 1,025,000,000,000,000,000,000,000,000,000 foot-tons. Making the same supposition as in the case of our cannon-ball, the final pressure would be that here stated.

15.Tyndall, J., Heat considered as a mode of Motion; Am. ed., p. 57, New York, 1863.

16.Rankine (The Steam-engine and other prime Movers, London, 1866,) gives the efficiency of Steam-engines as from 1-15th to 1-20th of the heat of the fuel.

Armstrong, Sir Wm., places this efficiency at 1-10th as the maximum. In practice, the average result is only 1-30th. Rep. Brit. Assoc., 1863, p. liv.

Helmholtz, H. L. F., says: “The best expansive engines give back as mechanical work only eighteen per cent. of the heat generated by the fuel.” Interaction of Natural Forces, in Correlation and Conservation of Forces, p. 227.

17.Thomsen, Julius, Poggendorff’s Annalen, cxxv, 348. Also in abstract in Am. J. Sci., II, xli, 396, May, 1866.

18.American Journal of Science, II, xli, 214, March, 1866.

19.In this calculation the annual evaporation from the ocean is assumed to be about 9 feet. (See Dr. Buist, quoted in Maury’s Phys. Geography of the Sea, New York, 1861, p. 11.) Calling the water-area of our globe 150,000,000 square miles, the total evaporation in tons per minute, would be that here given. Inasmuch as 30,000 pounds raised one-foot high is a horse-power, the number of horse-powers necessary to raise this quantity of water 3½ miles in one minute is 2,757,000,000,000. This amount of energy is precisely that set free again when this water falls as rain.

20.Compare Odling, Wm., Lectures on Animal Chemistry, London, 1866. “In broad antagonism to the doctrines which only a few years back were regarded as indisputable, we now find that the chemist, like the plant, is capable of producing from carbonic acid and water a whole host of organic bodies, and we see no reason to question his ultimate ability to reproduce all animal and vegetable principles whatsoever.” (p. 52.)

“Already hundreds of organic principles have been built up from their constituent elements, and there is now no reason to doubt our capability of producing all organic principles whatsoever in a similar manner.” (p. 58.)

Dr. Odling is the successor of Faraday as Fullerian Professor of Chemistry in the Royal Institution of Great Britain.

21.Marshall, John, Outlines of Physiology, American edition, 1868, p. 916.

22.Frankland, Edward, On the Source of Muscular Power, Proc. Roy. Inst., June 8, 1866; Am. J. Sci., II, xlii, 393, Nov. 1866.

23.Liebig, Justus von, Die organische Chemie in ihrer Anwendung auf Physiologie und Pathologie, Braunschweig, 1842. Also in his Animal Chemistry, edition of 1852 (Am. ed., p. 26), where he says “Every motion increases the amount of organized tissue which undergoes metamorphosis.”

24.Compare Draper, John Wm. Human Physiology.

Playfair, Lyon, On the Food of Man in relation to his useful work, Edinburgh, 1865. Proc. Roy. Inst., Apr. 28, 1865.

Ranke, Tetanus eine Physiologische Studie, Leipzig, 1865.

Odling, op. cit.

25.Voit, E., Untersuchungen über den Einfluss des Kochsalzes, des Kaffees, und der Muskelbewegungen auf den Stoffwechsel, Munich, 1860.

Smith, E., Philosophical Transactions, 1861, 747.

Fick, A., and Wislicenus, J., Phil. Mag., IV, xxxi, 485.

Frankland, E., loc. cit.

Noyes, T. R., American Journal Medical Sciences, Oct. 1867.

Parkes, E. A., Proceedings Royal Society, xv, 339; xvi, 44.

26.Smith, Edward, Philosophical Transactions, 1859, 709.

27.Authorities differ as to the amount of energy converted by the steam-engine. (See Note 16.) Compare Marshall, op. cit., p. 918. “Whilst, therefore, in an engine one-twentieth part only of the fuel consumed is utilized as mechanical power, one-fifth of the food absorbed by man is so appropriated.”

28.Heidenhain, Mechanische Leistung Wärmeentwickelung und Stoffumsatz bei der Muskelthätigkeit, Breslau, 1864.

See also Haughton, Samuel, On the Relation of Food to work, published in “Medicine in Modern Times,” London, 1869, Macmillan & Co.

29.Heidenhain, op. cit. Also by Fick, Untersuchungen über Muskel-arbeit, Basel, 1867. Compare also “Nature,” i, 159, Dec. 9, 1869.

30.Du Bois-Reymond, Emil, On the time required for the transmission of volition and sensation through the nerves, Proc. Roy. Inst. Also in Appendix to Bence Jones’s Croonian lectures.

31.Marshall, op. cit., p. 227.

32.Melloni, Ann. Ch. Phys., xlviii, 198.

See also Nobili, Bibl. Univ., xliv, 225, 1830; lvii, 1, 1834.

33.The apparatus employed is illustrated and fully described in Brown-Sequard’s Archives de Physiologie, i, 498, June, 1868. By it the 1-4000th of a degree Centigrade may be indicated.

34.Lombard, J. S., New York Medical Journal, v, 198, June, 1867. [A part of these facts were communicated to me directly by their discoverer.]

35.Wood, L. H., On the influence of Mental activity on the Excretion of Phosphoric acid by the Kidneys. Proceedings Connecticut Medical Society for 1869, p. 197.

36.On this question of vital force, see Liebig, Animal Chemistry. “The increase of mass in a plant is determined by the occurrence of a decomposition which takes place in certain parts of the plant under the influence of light and heat.”

“The modern science of Physiology has left the track of Aristotle. To the eternal advantage of science, and to the benefit of mankind it no longer invents a horror vacui, a quinta essentia, in order to furnish credulous hearers with solutions and explanations of phenomena, whose true connection with others, whose ultimate cause is still unknown.”

“All the parts of the animal body are produced from a peculiar fluid circulating in its organism, by virtue of an influence residing in every cell, in every organ, or part of an organ.”

“Physiology has sufficiently decisive grounds for the opinion that every motion, every manifestation of force, is the result of a transformation of the structure or of its substance; that every conception, every mental affection, is followed by changes in the chemical nature of the secreted fluids; that every thought, every sensation is accompanied by a change in the composition of the substance of the brain.”

“All vital activity arises from the mutual action of the oxygen of the atmosphere and the elements of the food.”

“As, in the closed galvanic circuit, in consequence of certain changes which an inorganic body, a metal, undergoes when placed in contact with an acid, a certain something becomes cognizable by our senses, which we call a current of electricity; so in the animal body, in consequence of transformations and changes undergone by matter previously constituting a part of the organism, certain phenomena of motion and activity are perceived, and these we call life, or vitality.”

“In the animal body we recognize as the ultimate cause of all force only one cause, the chemical action which the elements of the food and the oxygen of the air mutually exercise on each other. The only known ultimate cause of vital force, either in animals or in plants, is a chemical process.”

“If we consider the force which determines the vital phenomena as a property of certain substances, this view leads of itself to a new and more rigorous consideration of certain singular phenomena, which these very substances exhibit, in circumstances in which they no longer make a part of living organisms.”

Also Owen, Richard, (Derivative Hypothesis of Life and Species, forming the 40th chapter of his Anatomy of Vertebrates, republished in Am. J. Sci., II, xlvii, 33, Jan. 1869.) “In the endeavor to clearly comprehend and explain the functions of the combination of forces called ‘brain,’ the physiologist is hindered and troubled by the views of the nature of those cerebral forces which the needs of dogmatic theology have imposed on mankind.” * *

“Religion pure and undefiled, can best answer how far it is righteous or just to charge a neighbor with being unsound in his principles who holds the term ‘life’ to be a sound expressing the sum of living phenomena; and who maintains these phenomena to be modes of force into which other forms of force have passed, from potential to active states, and reciprocally, through the agency of these sums or combinations of forces impressing the mind with the ideas signified by the terms ‘monad,’ ‘moss,’ ‘plant,’ or ‘animal.’”

And Huxley, Thos. H., “On the Physical Basis of Life,” University Series, No. 1. College Courant, 1870.

Per contra, see the Address of Dr. F. A. P. Barnard, as retiring President, before the Am. Assoc. for the Advancement of Science, Chicago meeting, August, 1868. “Thought cannot be a physical force, because thought admits of no measure.”

Gould, Benj. Apthorp, Address as retiring President, before the American Association at its Salem meeting, Aug., 1869.

Beale, Lionel S., “Protoplasm, or Life, Matter, and Mind.” London, 1870. John Churchill & Sons.

37.For an excellent account of this distinguished man, see Youmans’s Introduction to the Correlation and Conservation of Forces, p. xvii.

38.Draper, J. W., loc. cit.

39.Henry, Joseph, Agric. Rep. Patent Office, 1857, 440.

40.Watters, J. H., An Essay on Organic, or Life-force. Written for the degree of Doctor of Medicine in the University of Pennsylvania, Philadelphia, 1851. See also St. Louis Medical and Surgical Journal, II, v, Nos. 3 and 4, 1868; Dec. 1868, and Nov. 10, 1869.

41.LeConte, Joseph, The Correlation of Physical, Chemical and Vital Force, and the Conservation of Force in Vital Phenomena. American Journal of Science, II, xxviii, 305, Nov. 1859.

42.Lombard, J. S., loc. cit.

43.Noyes, T. R., loc. cit.

44.Wood, L. H., loc. cit.

AS REGARDS PROTOPLASM, ETC.

PREFATORY NOTE.

The substance of the greater part of this paper, which has been in the present form for some time, was delivered, as a lecture, at a Conversazione of the Royal College of Physicians of Edinburgh, in the Hall of the College, on the evening of Friday, the 30th of April last.

It will be found to support itself, so far as the facts are concerned, on the most recent German physiological literature, as represented by Rindfleisch, Kühne, and especially Stricker, with which last, for the production of his “Handbuch,” there is associated every great histological name in Germany.

Edinburgh, October, 1869.