THE EFFECT OF CLIMATE AND WEATHER 303 



The second curve from the bottom in Figure i shows Prof. 

 L. L. Woodruff's measurements of the rate of fision among 

 the lowly one-celled infusorians known as paramoecium. 

 At 40° no fision and hence no reproduction take place, 

 higher temperatures are accompanied by increasingly 

 rapid fision until the optimum is reached between 80° 

 and 85°. In a still warmer environment reproduction dimin- 

 ishes rapidly and finally ceases at about 95°. The total 

 activity of animals like the crayfish may be measured by 

 their absorption of oxygen as shown in the next curve. 

 Here the phenomena are almost the same as in the other 

 cases, with an optimum at about 74°. 



The other four lines in Figure i represent human activity. 

 The lower, marked "Health" is based on the work of the 

 National Research Council's Committee on "Atmosphere 

 and Man." In shows the daily deaths of persons five years 

 of age and over in New York City on and immediately 

 after days having the temperatures indicated at the top. 

 It has been inverted so that the high portions mean good 

 health and low portions poor health. The resemblance of 

 this curve to those for plants and animals in unmistakable. 

 The only important difference is that the left-hand portion 

 tends to become horizontal at a level much higher than 

 that to which the other end descends. This merely indicates 

 that in cold weather mankind protects himself against low 

 temperature in a way that is impossible for other creatures. 

 At high temperatures how^ever, he does not protect himself 

 and therefore his health diminishes just as does that of 

 animals and plants. The highest point or optimum comes 

 when the temperature for day and night together averages 

 66° to 70°. Numerous other investigations give a similar 

 result except that the optimum appears on an average to be 

 slightly lower, namely an average of 64° or 6^° for the 

 entire twenty-four hours. 



The next curve, "Physical Energy," shows the amount 

 of piece-work accomplished by five hundred men and women 

 in Connecticut factories on days with various mean tempera- 

 tures. Its resemblance to the line for "Health" need hardly 

 be pointed out. There is the same tendency toward levelness 

 on the left, and the same rapid falling off at high tempera- 



