1871.] Change of Climate on the Human Economy. 297 



Table II. — To show the relative excretion of free fluid in Temperate 

 and Tropical latitudes. 



Organ. 



Temperate zone*. 



Tropics. 





oz. per cent, 

 (aooutj — — io^io — Oo Q-t 



(somewhat 



more than) £ = 20-50=26-97 

 (rather less 



than) T V= 6-50= 8-55 

 (about) 3- 75= 4-93 



oz. per cent. 



(aDOUE^ j- — Oi —'xZKj-i: 



(somewhat 



more than) ^ = 19-58 = 22-25 



■&=27*02=30*7 

 «V= 44 = 5- 



Skin 





While the urine thus decreases from 59 \ to 42 per cent., the perspiration 

 rises from 8| to 30 per cent., there being a slighter fall of 4^ per cent, from 

 the lungs, and a trifling rise from the bowels. The kidneys are thus the 

 chief eliminators of surplus water in the tropics as in temperate regions ; 

 but in the former it is the skin, as in the latter it is the lungs that rank 

 next. If suddenly stressed, however, by excessive imbibition, and the 

 safety-valve action of the kidneys or skin be brought into play, these pro- 

 portions doubtless differ. Will they hold good for permanent residents in 

 the tropics, foreign or native ? 



The increased perspiration in the tropics or in artificial heat, and dimi- 

 nished urinary and pulmonic water-excretion by 22 per cent., is equal to a 

 proportionate increase in the cutaneous circulation and corresponding with- 

 drawal of blood from the kidneys to the extent of 17 J per cent., and lungs 

 of 4J per cent. Moreover this diminished exhalation of watery vapour 

 from the lungs, by vicarious action of the skin, still further decreases the 

 amount of blood circulating through them, already shown to be reduced by 

 12*24 per cent., or 16*62 fl. oz. by a diminished excretion of carbonf. The 

 total decrease in the lung circulation is thus : — 



16*62 fl. oz. 

 + 6*42 „ (4-72 per cent.) 



= 23*04 fl. oz. as the total permanent withdrawal of blood 

 from the lungs by an average temp, of 80-83° F. 

 These facts appear highly interesting in the etiology of these and other 

 important internal and external organs, as well as hygienically and thera- 

 peutically suggestive. 



The following results of the entire voyage from Bahia to England on a 



* Hooper, ' Physicians' Vade Mecum.' In Dalton's experiment the amount of free 

 fluid drunk was 76 oz., and in the above 88 oz. daily. The proportionate results, 

 however, are the same in both. 



t Proc. E, S. 1870, vol. xviii. p. 515. 

 VOL. XIX. 2 A 



