R ESPIRA TION. 4 1 1 



records a difference of 1.5° to 2°. The figures by other observers vary from 

 0.5° to 1.5°. The larger the volume of air respired, other things being equal, 

 the less the increase of temperature. 



The volume of expired air is from 10 to 12 per cent, greater than that of 

 inspired air, this increase being due to expansion caused by the increase of tem- 

 perature. When dried and proper deductions made for temperature and baro- 

 metric pressure, the actual or corrected volume is less by about ^ to -£$. 



Lossen estimated that 0.0204 gram of ammonia is eliminated per diem in 

 the expired air. Bergey also found small quantities of ammonia, yet Voit's 

 investigations indicate that expired air usually does not contain even a trace 

 of ammonia. 



Alterations in the Gases in the Blood. — The blood in the pulmonary 

 artery is of the typical venous color — that is, deep bluish-red. During its 

 passage through the lungs it becomes scarlet-red, or, commonly speaking, arte- 

 rialized or aerated. If we take arterial blood and deprive it of oxygen, the 

 color changes to a venous hue ; if now we shake the bluish-red blood in air or 

 O, the scarlet-red color is restored. We have here the suggestion that the blood 

 while passing through the lungs absorbs O. Analyses show that not only 

 does absorption of O occur, but that there is simultaneously with this an 

 elimination from the blood of C0 2 . 



A rterial and venous blood each contains approximately 60 volumes per cent, 

 of O and C0 2 ; that is, for about every 100 volumes of blood 60 volumes of 

 gas will be obtained. Such analyses demonstrate also that while the total 

 volumes per cent, of O and CO, are about the same, the proportions are 

 different. The following table, compiled from various sources, gives the 

 volumes per cent, of gases in the arterial blood of various animal- : 



Animal. Total. O. CO-,. N. 



Dog 59.38- 18.65 38.93 1.8 



Cat 43.2 13.1 28.8 1.3 



Sheep 57.6 10.7 45.1 1.8 



Rabbit 49.3 13.2 34.0 2.1 



Man 63.4 21.6 40.3 1.5 



Fowl 58.8 10.7 48.1 



Pflviger obtained as averages of analyses of arterial blood of dogs 58.3 

 volumes per cent., consisting of 22.2 volumes per cent, of O, 34.3 volumes 

 per cent, of C0 2 , and 1.8 volumes per cent, of N. Venous blood, according 

 to estimates by Zuntz based on a large number of analyses, contains 7.15 vol- 

 umes per cent, less of O and 8.2 volumes per cent, more of C< I,. The quantity 

 of N is practically the same in both arterial and venous blood. 



The proportions of O and CO a in arterial blood vary but little in speci- 

 mens taken at random from the arterial system, while those of venous blood, 

 on the contrary, differ considerably according to the locality of the vessel as 

 well as to the degree of activity of the structures whence the Mood come-. 

 Thus, venous blood from an active secreting gland differs very little in its 

 composition, gaseous and otherwise, from typical arterial blood, whereas when 



