CHAP. IX.] THE CONTBACTILE TISSUES. 407 



along the fibres ; it must satisfy us as to the actual method of shorten- 

 ing as to the momentary disturbance of the structural elements of 

 the fibre; and, finally, it must account for the origin of the heat, 

 electrical disturbance and mechanical motion which are characteristic 

 of muscular contraction, and suggest some relationship among them. 

 Most theories have been content to explain one or other of these 

 points without attempting the whole. 



The point which most nearly concerns the physiological chemist 

 is the last mentioned, viz. the origin and interdependence of the heat, 

 electrical tension and mechanical motion of contraction, and this 

 alone will be considered in the present chapter. The probable nature 

 of nervous action will receive consideration elsewhere in this book ; 

 and the views of observers as to the appearances of contracting muscle 

 beneath the microscope will be found in Manuals of Histology. 



John One of the most remarkable anticipations of modern 



Mayow. discovery and opinion occurs in the works of John 



Mayow, published in 1668 1674 1 . Exactly one hundred years before 

 the discovery of oxygen, Mayow demonstrated by a series of con- 

 clusive experiments, that some portion or constituent of the air is 

 necessary to combustion, and that the same substance is equally 

 indispensable to living animals. To this portion of the air he gave 

 the name of particulae igneo-aereae. The same substance enters into 

 the composition of nitre ; since, when nitre is present, combustible 

 bodies can inflame and burn even in vacuo or beneath water. Hence 

 Mayow called the igneo-aerial particles, nitro-aerial particles and nitro- 

 aerial spirit. This substance, though indispensable to combustion, 

 does not itself burn ; but when antimony is calcined in the focus of a 

 burning-glass, or by exposure to the flame of nitre, the antimony 

 becomes not a little increased in weight a circumstance which Mayow 

 could only explain by supposing the fixation of igneo-aerial particles in 

 the calcined antimony 2 . Respiration introduces igneo-aerial particles 

 into the blood, where they meet with saline-sulphureous (i.e. combusti- 

 ble) particles and produce the animal heat 3 . From the blood the igneo- 

 aerial particles are conveyed to the muscles 4 , where they meet with 



1 John Mayow, Tractatus quinque Medico-physici. Oxford, 1674. 



2 J. Mayow, de Sal-nitro et spiritu nitro-aereo, Chap. iii. p. 28. "Hue etiam facit, 

 quod Antimonium non tantum a Spiritu Nitri, radiisque solaribus, sed etiam a flamma 

 nitri, in qua particulae nitro-aereae densius agglomerantur, virtutem Diaphoreticam 

 acquirit. Neque illud praetereundum est, quod Antimonium, radiis solaribus calcinatum, 

 haud parum in pondere augetur; uti experientia conipertum est: quippe vix concipi 

 potest, unde augmentum illud Antimonii, nisi a particulis nitro-aereis, igneisque ei inter 

 calcinanduni infixis, procedat." 



3 Ibid., Chap. viii. p. 151. 



4 J. Mayow, de Motu Musculari et spiritibus animalibus, Op. cit., part ii. p. 3. 

 " Spiritum nitro-aereum respirationis ope in Cruoris massam transmitti, Sanguinisque 

 Fermentationem, et Incalescentiam ab eodem provenire, alibi a nobis ostensum est. lam 

 vero circa usum Spiritus istius inspirati addo insuper, quod idem in Motibus Animalibus 

 instituendis partes primarias sortiatur : quam quidem opinionem a me jam olim in 

 medium prolatam, etiamnum firmiter retineo, non quod praeconceptae Hypothesi man- 

 cipatus, earn, uti moris est, mordicus defendere constitui, sed quod eandem rationi 

 maxime consentaneam arbitror." 



