APPENDIX II. 153 



total of work, but must appear entirely in the form 

 of heat, since all the mechanical effects of these 

 movements are immediately undone again. If we 

 raise an arm, we immediately let it drop again, &c. 



' k There was besides a large portion of our mus- 

 cular system employed during the ascent, which was 

 performing no external work (not even temporary 

 work, or mechanical effects immediately reversed), 

 but which [cannot be employed without the same 

 force-generating processes which render external 

 work possible. As long as we hold the body in an 

 upright position, individual groups of muscles (as, 

 for instance, the muscles of the back, neck, &c.) 

 must be maintained in a state of continual tetanus 

 in order to prevent the body from collapsing. We 

 may conceive of a tetanized muscle as holding up a 

 weight which would immediately fall if the supply 

 of actual energy were to cease. It is active but it 

 performs no work, and therefore all the force pro- 

 duced is liberated in the form of heat." 



Thus the total amount of measured and estimable 

 work performed in 5*5 hours in the experiments 

 before us was 159,637 metrekilograms for Fick, and 

 184,287 metrekilograms for Wislicenus. This is 

 our second datum. 



3rdly. The third, viz., the amount of muscle oxidized 

 in the body during the performance of this work has 

 been carefully determined by the same experiment- 

 ers, as well as the rate of muscle consumption before 

 and after the ascent. For the details of these de- 

 terminations the speaker referred his hearers to the 

 Philosophical Magazine for 1866, vol. xxxi., page 



