PLAYFAIR, LYON, On the Food of Man in relation to his useful
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, onefifth 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.