the Blood in Muscular Work. 345 



these compounds as are capable of it contributes to the heat, 

 and probably to the work also of the body. Professor Haughton, 

 in his well-known papers on Diabetes mellitus*, while he as- 

 sumes that the normal disintegration of tissue is an oxidation, 

 suggests that in the diseased state a large portion of the tissue 

 is not oxidized, but is simply decomposed into urea and sugar. 

 Mayer's view compels us to believe that this, or something like 

 this, is the normal process, and consequently that the pheno- 

 mena of diabetes, as far as they are independent of the nature of 

 the food, must be due either to increased disintegration or to 

 diminished oxidation, or possibly to the conjunction of both 

 causes. He found that increased excretion of urea went hand 

 in hand with the presence of sugar in the urine ; but as the food 

 of the patients was increased from two- to four- fold, the observa- 

 tion does not prove much. The great bulk of the nitrogen of 

 the food must be excreted as urea. 



I will not speculate on the mode in which force developed in 

 the blood is capable of producing contraction in the tissue. The 

 process is subject to the control of the nerves, and is probably 

 connected with the production of electricity; bat one conclusion 

 seems so probable that I cannot help suggesting it. It has long 

 been known that muscular contraction is invariably attended 

 with increased muscle-metamorphosis. Liebig, Helmholtz, 

 Du Bois Reymond, Ranke, and others have left no doubt upon 

 this point ; and it may even be considered to be proved that in- 

 creased work is attended with a slight though irregular increase 

 in the excretion of nitrogen ; for though in Fick and "Wislice- 

 nus's experiment, as well as in many previous ones, this result 

 was not observed, its absence has been shown to be due to the 

 shortness of the time during which the observation was made, 

 and in the recent careful experiments of Dr. Parkesf, in which 

 this source of error was eliminated, the increase was clearly 

 shown. 



What, then, is the cause of this increase? It is obviously 

 absurd to attribute it to mere mechanical friction of the muscle- 

 fibres, to ordinary wear and tear; audit therefore seems natural 

 to ascribe it to the excess of force which remains after the per- 

 formance of the work. That an excess of force is always deve- 

 loped is certain ; and though much of it may afterwards assume 

 the form of heat, it seems not improbable that some part may 

 be spent in producing chemical decomposition, and so be once 

 more stored up as potential energy. It appears indeed possible 

 that all normal muscular disintegration, inasmuch as it is sub- 

 ject to the influence of the nerves and attended with electrical 



* Dublin Quarterly Journal of Medical Science, vols. xxxi. xxxii. xxxv. 

 t Proc. Roy. Soc. vol. xv. p. 339. 



