354 PHILOSOPHY OF ZOOLOGY. 
subject with great attention, was led from his experiments 
to conclude, that moderate exercise increased the consump- 
tion of oxygen, but if continued so as to induce fatigue, it 
occasioned diminution. The exhilarating passions appear 
likewise to increase the quantity, probably by exciting mus- 
eular action. On the other hand, the depressing passions 
and sleep, aleohol *, and tea, diminish the quantity. 
Dr Prout likewise found, that the quantity of oxygen 
consumed, is not uniformly the same during the twenty-four 
hours; but is always greater at one and the same part of 
the day than at any other. He determined, that its maxi- 
mum occurs between 10. a. m. and 2. p. m., or generally be- 
tween 11. a. m.and 1. p. m., and that its minimum commen- 
ces about 8? 30’ p. m., and continues nearly uniform tll 
about 34 30’ a.m. He is inclined “ to believe, that the 
presence and absence of the sun alone regulate these varia- 
tions.” Here it may be observed, that in diurnal animals, 
the forenoon, during which it appears that the consumption 
of oxygen is at its maximum, is the period of activity or 
muscular exertion ; while in the afternoon, in which the con- 

* Dr Prout found that “‘ alcohol, in every state and in every quantity, 
uniformly lessens, in a: greater or less degree, the quantity of carbonic acid 
elicited, according to the quantity and circumstances under which it is 
taken.” ‘This result is certainly the reverse of what might have been ex-. 
pected, considering the temporary exhilarating effects of spirituous liquors. 
That the quantity should be found diminished, after the exhilarating effects 
of the alcohol had ceased, and the consequent depression had taken place 
was precisely what might have been expected, and which the experiments of 
Dr Fire realize. ‘¢ On the 8th of June, (says Dr Fire) a much greater 
quantity of wine than usual was taken, and the next day the quantity of 
carbonic acid was repeatedly found as low as above stated, (5.75 per cent.). 
On making the experiment again with less wine, the quantity of carbonic 
acid was considerably reduced, though not so much as before,” (only be- 
tween 2 and 3 per cent.) ib, iv. 335: This diminished. state certainly indi- 
cates a previous excess. The apparent discordance of the. results of these 
experimenters probably arises from peculiarities of habit or constitution. 
