Z-//'^. 



THE BEGINNINGS OF LIFE. 



33 



1 



c riiuscul^j ^^ position to the doctrines of Liebig, that the heat which 



is transformed into mechanical energy is by no means 



°f t^^^ latter; 

 ^ the most 



-instructed i 



er 11 



IS 



^f tl^e total ai 

 w know also 



It 



necessarily derived from the combustion of nitroge- 

 nous substances j and, least of all, from an oxidation 

 of the substance of the muscle itself. This doctrine of 

 Liebig, which was for a long time accepted by many 

 physiologists, was from the commencement rejected by 



r 



a few, and notably so by Mayer, in his celebrated 

 memoir before alluded to ^. In this memoir he insisted 

 pnetk ^^^ — ^ A muscle is only an apparatus by means of 



c, only fromJ.to y rr y 



in<^ itself as mtdi which the transformation of force is brought about, 



but it is not the substance by the chemical change of 

 which the mechanical effect is produced/ The recent 

 admirable researches of MM. Fick and Wislicenus ^ 



!crs ^ as the mi 

 be about ^'^oftk 



t says (loc. cit.p.if 



zx^ de perfection f are entirely in favour of this notion. They found, in 



ention, surlarapi making a mountain ascent, that the total combustion 



-ar certains obeaiu ^£ nitrogenous materials would only suffice to produce 



es J^^^"^_^^^^ ^^j. about one-half of the total effective energy which must 



jifreon messager* have been expended during the excursion. This and 



ne de pied en sii- other considerations render it almost certain that the 



5 d^crivantnii j^^^^ which is converted into mechanical energy during 



..insectesdont 



tenu q.e «p." 



souslalig"^'' 

 jours api^s 

 inporte ^\! 



comme les taons peuvent suivre pendant de longnes heures un cheval 

 lance au grand trot. Par une belle journ^e de mai ou de juin Tabeille 

 vole d'une manibre continue du matin au soir, pour aller cueillir dans les 

 coroUes des fleurs et rapporter k la ruche les materiaux necessaires aux 



Malte et r^ [ travaux et a la nourriture de la communautc?.' 

 , _„ due"'. 1 . r\.„o„;„ A/r .• -.^T^^, ,• . ,, 





1S45. 



Organic Movement in its Relation to Material Changes/ Heilbronri 



* Philosophical Magazine,' vol. xxxi. p. 485. For most important 



{ 5 mou^^^^' ,[ additional facts and explanations, see a paper by Prof. Parkes in 'Pro- 

 '^ en i^^^^'^ ceedings of the Royal Society/ 1867, pp. 53-59. 



^part. 



^Ccri^^' 



