6 



Dr. A. Rattray on the Effects of 



[Nov. 21, 



placing, and air the displaced agent. It is in the blood that the fluc- 

 tuation originates : when heat attracts this surfacewards, the amount 

 drawn from the luugs is replaced by an equivalent bulk of air ; under cold, 

 which repels the blood inward, the air is again displaced by an equivalent 

 of blood*. 



Contrary to previous conviction, based on limited experiment, this 

 variation in the spirometric measurement of the lungs is no index of the 

 effect of change of climate on the ordinary breathing. Table III. shows 

 that the latter, instead of deepening by heat like the former, does the 

 reverse, and becomes gentler. As part of the same general physiological 

 process, reflection points to this as the more likely sequel, and reconciles 

 these apparently conflicting though allied phenomena. 



Table IV.f 





South temperate zone. 

 Lat. 35 . 

 Temp. 54 F. 



Tropics. 

 Near Equator, 

 Temp. 82 F. 



A. E., set. 40. | 

 Average of 12 ordinary I 

 respirations. 



3 p.m. J 



cubic inches. 

 H'54 



cubic inches. 

 13-25 



Thus my respirations averaged 14J cubic inches in 54° I\, and only 

 13| cubic inches in 82° E., L e. less than 1'29 cubic inch. So that even 

 if the respirations remained at 15| per minute, this alone would reduce 

 the air used by 28,792 cubic inches, =16-66 cubic feet, per day. 



Table V. confirms former observation that respiration is shiver in 



the tropics. 





Lat, 33 S. 

 Temp. 56 F. 



Equator. 

 Temp. g 2 c F. 



Lat. 53 N. 

 Temp. 54 F. 



Average of 15 f Rattray, £et. 40 



minutes at \ Downer, set. 31 



No. 

 16 

 17 

 *9 



No. 



15- 6 



1 6- 6 

 16-2 



No. 



16- 5 

 i8- 5 



17- 5 





17*3 



16-1 



i7'5 



* This derivative action of heated air on the lungs corresponds to that of other deri- 

 vatives, e.g. a hot bath increases their spirometric measurement by several cubic inches ; 

 so does a sodorific dose of Dover's powder. Ordinary slow and prolonged exercise does 

 the same by drawing blood to the functionally active muscles; and under violent 

 exercise and a perspiring skin it rises from 10 to 15 cubic inches, even when the second 

 result is taken in the evening, when the reduced temperature should have lessened it in 

 accordance with the law of climate. This effect of exercise, however, is not so marked 

 in the tropics as in temperate regions. 



t This experiment was made by means of an easily inflated bladder, from which the 

 air was measured by a graduated glass cylinder. 



