CHAP. IX.] THE CONTRACTILE TISSUES. 400 



the close of the last century, the importance of Mayow's work was 

 proclaimed by the enthusiasm of Dr Beddoes 1 and Dr Yeats 2 ; and in 

 1864, at a time when the theory of muscular activity had already 

 received its present bent, the acute speculations of Mayow in refer- 

 ence to it were again most honourably made known by Professor 

 Heidenhain 3 . 



It would be pushing literary justice to the extreme verge of pedantry to 

 pretend to find in authors earlier than Mayow the germs of a theory which 

 they were not in a position even to comprehend ; still it is interesting to 

 observe that the general idea of a combustion of matters within the body, 

 upon which the powers of life depend, is to be found in a book with which 

 Mayow was probably familiar. Francis Bacon, in his Historic*, Vitae et 

 Mortis, taught that all living beings contained two kinds of spirits, spiritus 

 mortuales which fill inanimate objects, and spiritus vitalis which confers life. 

 The doctrine of a vital principle stirring and regulating the members of 

 living creatures had existed, in one form or another, from the earliest times ; 

 but more than this Bacon taught that the spiritus vitalis exhibited a certain 

 incensio, or combustion, which gave rise to peculiar motions and powers. 

 "In omnibus aniniatis duo sunt genera spirituum : spiritus mortuales, quales 



insunt inanimatis ; et superadditus spiritus vitalis Sunt autem duo 



discrimina praecipua inter spiritus mortuales et spiritus vitales Alterum 



discrimen inter spiritus est ; quod spiritus vitalis nonnullam habeat incensi- 

 onem, atque sit tanquam aura composita ex flamma et ae're ; quemadmodum 

 succi animalium habeant et oleum et aquam. At ilia incensio peculiares 

 praebet motus et facilitates; etenim et fumus inflammabilis, etiain ante 

 flammam conceptam, calidus est, tenuis, mobilis; et tamen alia res est, 

 postquam facta sit flamma ; at incensio spirituum vitalium multis partibus 

 lenior est quam mollissima flamma, ex spiritu vini, aut, alias; atque 

 insuper mixta est, ex magna parte, cum substantia ae'rea ; ut sit et flammae 



et aereae naturae mysterium ...Neque tamen ulla ex ipsis actioni- 



bus unquam actuata foret (i. e. of the stomach, liver, heart, brain etc.), 

 nisi ex vigore et praesentia spiritus vitalis et caloris ejus 4 ." 



The obvious and extreme importance of air for the support of life, 

 and the muscular weakness which follows excessive bleeding, did not 

 escape the earliest observers, and were the foundation of hypotheses which 

 have been thought to foreshadow the modern view 5 . 



After the time of Mayow, the doctrine of muscle was 



Glisson. mainly given over to the Stahlists. Armed with his 



conception of an immaterial and rational anima endowed 



with unlimited spontaneous powers over matter, Stahl explained 



nearly all things with equal facility, and among them muscular 



1 Thomas Beddoes, Chemical Experiments and Opinions extracted from a work 

 published in the last century. Oxford, 1790. 



2 G. D. Yeats, Observations on the claims of the Moderns to some discoveries in 

 Chemistry and Physiology. London, 1793. 



3 Heidenhain, Mechanische Leistung, etc. Leipzig, 1864. 



4 Francis Bacon, Historia Vitae et Mortis, 1(323, Can. iv. and v. "Works," by 

 Spedding, Ellis and Heath, 1857, Vol. n. p. 214. 



5 Al. von Humboldt, Versuche u. die gereizte MusJcel- und Nervenfaser, Yol. n. pp. 

 91, 93. 1797. 



