176 APPENDIX II. 



bees and butterflies as instances of insects performing 

 enormous muscular work, and subsisting upon a diet 

 containing but the merest traces of nitrogen. 



CONCLUSION. 



llthly. We thus arrive at the following conclu- 

 sions : 



1. The muscle is a machine for the conversion of 

 potential energy into mechanical force. 



2. The mechanical force of the muscles is derived 

 chiefly, if not entirely, from the oxidation of matters 

 contained in the blood, and not from the oxidation 

 of the muscles themselves. 



3. In man the chief materials used for the pro- 

 duction of muscular power are non-nitrogenous ; but 

 nitrogenous matters can also be employed for the 

 same purpose, and hence the greatly increased 

 evolution of nitrogen under the influence of a flesh 

 diet, even with no greater muscular exertion. 



4. Like every other part of the body, the muscles 

 are constantly being renewed ; but this renewal is 

 not perceptibly more rapid during great muscular 

 activity than during comparative quiescence. 



5. After the supply of sufficient albuminized 

 matters in the food of man to provide for the neces- 

 sary renewal of the tissues, the best materials for 

 the production, both of internal and external work, 

 are non-nitrogenous matters, such as oil, fat, sugar, 

 starch, gum, &c. 



6. The non-nitrogenous matters of food, which 

 find their way into the blood, yield up all their 

 potential energy as actual energy ; the nitrogenous 



