10 



Effects of Climate on the Human Economy. [Nov. 21, 



Both the number who grew and the amount of increase were thus least 

 in the tropics. These detrimental fluctuations necessarily affect both 

 body and brain. If, therefore, we would produce strong, healthy, long- 

 lived officers and seamen, fit for any work or climate, we should not send 

 them unnecessarily to warm regions while as yet undeveloped lads. 



The following are the chief results and inferences of these experiments : — 



1st. The primary effect of great changes of climate is on the circulation, 

 the blood being drawn surfaceward by heat and driven inward by 

 cold. 



2nd. The secondary and local results are an increase or decrease in the 

 vascularity and function of the various tissues and organs of the 

 entire body — the external increasing under heat, internal under cold, 

 and vice versa. 



3rd. Hence in the tropics the vascularity of the adult lungs is reduced by 

 an average of 12 or 13 fluid oz. ; their spirometric measurement by 

 an average of 23 cubic inches ; their function by 18*43 per cent., i. e. 

 the use of 36*85 cubic feet less of air daily, excretion of 1*84 oz. less 

 carbon, and 6* 57 per cent, less of watery vapour. 



4th. Hence, also, the nephritic vascularity and secretion are reduced in 

 the tropics by 17| per cent., and those of the skin increased by 24 

 per cent. 



5th. In unison with the respiration the circulation is more languid in the 

 tropics, as indicated by the reduced (several beats) and perhaps less 

 forcible pulse. 



6th. Notwithstanding the reduced circulatory and respiratory functions, 

 and increased cutaneous exhalation, the temperature of the surface, 

 and perhaps that of the blood and body generally, rises about 2° F. 

 under tropical heat. 



7th. The organs and functions of animal, like those of vegetable, life are 

 affected by great changes of climate, — heat impairing the weight, 

 strength, and health, i. e. the physique, at all ages and retarding 

 growth in youth ; while cold has an opposite effect. 



8th. For obvious reasons these results vary with sex, temperament, size, 

 &c. ; and are most evident in the adult, decreasing towards either 

 extreme of life. 



9th. Collectively these changes are salutary, and meant to assimilate the 

 various organs, functions, and body of the inhabitants of one zone to 

 those of native races, to meet the requirements of the foreign climate^ 

 for which they are not, and perhaps never can be altogether, physio- 

 logically fitted. 



