138 CHANGES OF AIR AND BLOOD IN RESPIRATION. 



hundred cubic feet (22*65 cubic metres) of air for each person, unless the con- 

 ditions be such that the air is changed with unusual frequency ; for in ad- 

 dition to the actual loss of oxygen in the respired air, emanations from both 

 the pulmonary and cutaneous surfaces are constantly taking place, which 

 should be removed. In some institutions as much as twenty-five hundred 

 cubic feet (70*79 cubic metres) of air are allowed for each person. 



The quantity of oxygen consumed is subject to great variations, depend- 

 ing upon temperature, the condition of the digestive system, muscular activ- 

 ity etc. The following conclusions, the results of the observations of La- 

 voisier and Seguin, give at a glance the variations from the above-mentioned 

 causes : 



" 1. A man, in repose and fasting, with an external temperature of about 

 90 Fahr. (32*5 C.), consumes 1,465 cubic inches (24 litres) of oxygen per 

 hour. 



" 2. The same man, in repose and fasting, with an external temperature 

 of 59 Fahr. (15 C.), consumes 1,627 cubic inches (26-66 litres) of oxygen 

 per hour. 



" 3. The same man, during digestion, consumes 2,300 cubic inches (37*69 

 litres) of oxygen per hour. 



" 4. The same man, fasting, accomplishing the labor necessary to raise, in 

 fifteen minutes, a weight of about 16 Ib. 3 oz. (7*343 kilos.) to the height of 

 656 feet (200 metres) consumes 3,874 cubic inches (63-48 litres) of oxygen per 

 hour. 



" 5. The same man, during digestion, accomplishing the labor necessary 

 to raise, in fifteen minutes, a weight of about 16 Ib. 3 oz. (7*343 kilos.) to the 

 height of 692 feet (211*146 metres), consumes 5,568 cubic inches (91*24 litres) 

 of oxygen per hour." 



All who have experimented on the influence of temperature upon the con- 

 sumption of oxygen, in the warm-blooded animals and in the human subject, 

 have noted a marked increase at low temperatures. Immediately after birth 

 the consumption of oxygen in the warm-blooded animals is relatively very 

 slight. Buffon and Legallois have shown that just after birth, dogs and 

 other animals will live for half an hour or longer under water ; and cases are 

 on record in which life has been restored in newborn children after seven, 

 and it has been stated, after twenty- three hours of asphyxia (Milne-Edwards). 

 During the first periods of existence the condition of the newly born is near- 

 ly that of a cold-blooded animal. The lungs are relatively very small, and it 

 is some time before they fully assume their office. The muscular movements 

 are hardly more than are necessary to take the small quantity of nourishment 

 consumed at that period, and nearly all of the time is passed in sleep. There 

 is also very little power of resistance to a low temperature. Although accu- 

 rate researches regarding the comparative quantities of oxygen in the venous 

 and arterial blood of the foatus are wanting, it has been frequently observed 

 that the difference in color is not so marked as it is after pulmonary respira- 

 tion has become established. The direct researches of W. F. Edwards have 

 shown that the absolute consumption of oxygen by very young animals is 



