CALORIFIC INFLUENCE OF FOOD. 179 



last, the generation of heat wholly ceasing, the temperature gave way 

 rapidly just previous to death. 



If, therefore, it was possible for life to continue without the evolution 

 of animal heat, it would be with the body as it is with the stem of a tree. 

 It would follow the thermometric variations in the air, the maxima of 

 heat and cold being somewhat later than the aerial ones, and within nar- 

 rower limits, by reason of the low conducting power. The nearest ap- 

 proach to this is in cases of absolute starvation, and though in man the 

 effect is masked by the due taking of food, it none the less exists. In 

 human communities there is some reason beyond mere cus- influence of 

 torn which has led to the mode of distributing the daily 

 meals. A savage may dispatch his gluttonous repast, and ature. 

 then starve for want of food ; but the more delicate constitution of the 

 civilized man demands a perfect adjustment of the supply to the wants 

 of the system, and that not only as respects the kind, but also the time. 

 It seems to be against our instinct to commence the morning with a 

 heavy meal. We break fast, as it is significantly termed, but we do 

 no more, postponing the taking of the chief supply until dinner, at the 

 middle or after part of the day. If men were only guided by views of 

 economy of time saved for the pursuits of business, or if, on this occasion, 

 they put in practice the rule they observe on so many others, of never 

 postponing the gratification of their desires, the first affair of the morn- 

 ing would have been an abundant repast. But against this something 

 within us revolts, and that in all classes, the laboring, the intellectual, 

 the idle. I think there are many, reasons for supposing, when we recall 

 the time which must elapse between the taking of food and the comple- 

 tion of respiratory digestion, that this distribution of meals is not so 

 much a matter of custom as an instinctive preparation for the systemic 

 rise and fall of temperature attending on the maxima and minima of daily 

 heat. The light breakfast has a preparatory reference to noonday, the 

 solid dinner to midnight. 



Once more I would remark, that we must not be deceived by the 

 masked aspect which the system in this matter presents, connection of 

 Its diurnal variations are concealed by agencies brought variations of 



. . , iL L-ut j. heat with or- 



specially into operation for that purpose, but they exist in gan i c p er iodi- 

 the physical necessities of the case ; and herein, I believe, cities - 

 we have a first glimpse of the cause of those periodicities, which physi- 

 cians from the earliest times have remarked ; for, though the nervous 

 system, both in a state of health and disease, may seem to be their ori- 

 gin, it is not impossible that its changes are connected with variations 

 thus taking place in the external world. 



We have next to consider the effect of the annual varia- Annual varia- 

 tions of temperature, which reach their maximum soon after tions of heat - 



