1870.] BARKER — ON VITAL AND PHYSICAL FORCES. 435 



Animal Chemistry, editicm of 1852 (Am. ed. p. 2G), where he says 

 " Every motion increases the amount of organised tissue which undergoes 

 metamorphosis." 



24 Compare Draper, John TVm., Hbiman Physiology. 



Playfair Lyon, On the Food of Man in relation to his useful work 

 Edinburgh, 1865. Proc. Roy. Inst., April 28, 1865. 

 Ranke, Tetanus eine Physiologische Studie, Leipzig, 1865. 

 Odling, OJ). cit. 



25 YoiT, E., Uutersuchungen iiber den Einfluss des Kochsalzes, des 

 Kaffees, und der Muskelheweguugeu auf deu StofFwechsel, Munich, 

 I860. 



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



FiCK, A., and Wmlicenus, J., Phil. Mag., IV, \x\, 485. 



Frankland, E., loc. cit. 



Is"oYEs, T. R., American Journal Medical Sciences, Oct., 1867. 



Parkks, 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 Xote 16.) Compare Marshall, oj). cit., p. 9 J 8. 

 '* Whilst, therefore, in an engine one-twentieth part only of tlie fuel 

 consumed is utilized as mechanical power, one-fifth of the food absorbed 

 by man is so appropriated."' 



28 Heidenhain, Mechanische Leistung Wiirmeeutwickelung und 

 Stoffumsatz bei der Muskelthatigkeit, Breslau, 1864. 



See also Haughton Samuel, on the Relation of Food to "Work, pub- 

 lished in " Medicine in Modern Times," London, 1869, Macmillan & Co. 



29 Heidenhain, op. cit. Also by Fick, Untersuchungen iiber Muskel- 

 orbeit, Basel, 1867. Compare also " is^ature," i, 159, Dec. 9, 1969. 



30 Du Bois-Raymond, Emil, On the time required for the trans- 

 mission of volition and sensation through the nerves, Proc. Roy. Inst. 

 Also in Appendix to Bence Jones's Croouiau lectures. 



31 Marshall, ojy. cit., p. 227. 



32 Melloni, A-un. Ch. Phys., xlviii, 198, 



See also Xobili, Bibl. Univ., xliv, 225, 1830; Ivii, 1, 1834. 



33 The apparatus employed is illustrated and fully described in Brown- 

 Sequard's Archives de Physiologic, i, 498, June, 1868. By it the l-4000th 

 of a degree Centigrade may be indicated. 



34 Lombard, J. S., Ne^ York Medical Journal, v. 198, June, 1867. 

 [A part of these facts were communicated to me directly by their dis- 

 coverer. ] 



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. 



