284 BIOLOGICAL PROBLEMS 



" drying power", or capacity for taking up moisture, 

 by reason of the fact that it is already nearly saturated. 

 And so, while the temperature of the vitiated air rises, 

 the chief means of cooling the body is thrown out of 

 action by the concomitant increase in the moisture of 

 the atmosphere, and slight heat retention takes place, 

 with symptoms of inattention, listlessness, restless- 

 ness, poor work, and headache. Thus, in a hot room, 

 more blood is sent to the skin for heat-regulating pur- 

 poses, and the activity of the countless sweat glands 

 is increased ; but if the heat loss is interfered with, as 

 it is in a crowded ill -ventilated room, along with 

 a lowered blood pressure there is an accelerated pulse 

 beat, and the whole metabolism of the body is affected 

 by the heat retention, and if work is done it is per- 

 formed under handicapping bodily circumstance. 



The distaste for physical labour upon a hot, humid 

 day has a deeper basis than mere disinclination the 

 muscles are physically incapable of performing their 

 best work. The effect of the accumulation of fatigue 

 products, acting toxically in reducing the activity of 

 the tissues, is increased by the raised body tempera- 

 ture. The effect of moist heat upon the muscular 

 power has been tested and gauged by several workers. 

 Lee and Scott found in respect to cats exposed for six 

 hours to atmospheric conditions varying only in re- 

 spect to the temperature and humidity, that muscles 

 removed immediately after such exposure, and stimu- 

 lated to exhaustion, showed a progressive decrease 

 in the average duration of their working power and 

 of the amount of work performed, as the temperature 

 and humidity of the air were raised from 70 F. and 

 5.2 per cent respectively, to 91 F. and 90 per cent. 

 It has also been found (Patrizi) that human muscles, 

 when heated by localized hot baths, are subject to 

 early fatigue and exhaustion. 



