TENSION-EQUALIZER AND SPIROMETER UNITS. 



117 



This calculation has been made for all the five factors observed, not 

 only for a variation of 0.5 per cent but also for variations of 1 per cent, 

 1.5 per cent, 2 per cent, and so on. The results of these calculations 

 with both forms of apparatus are given in the probability curves shown 

 in figure 37, the ordinates representing the percentage of the total 

 number of periods, the abscissae representing the percentage variation of 

 the number of periods indicated. The percentage of the total number of 



CARBON DIOXIDE ELIMINATED - 



OXYGEN ABSORBED- 



RESPIRATORY QUOTIENT- 



a 



8 9 10 I 2 3 



PER CENT OF VARIATION 



Fio. 37. — Probability curves for the series of comparison experiments with the spirometer unit 



and the tension-equalizer unit. 



The ordinates indicate the percentage of the total number of periods; the abscissa: indicate 

 the percentage of variation from the average. 



periods is plotted in intervals of 5 per cent and the percentage varia- 

 tion in intervals of 0.5 per cent. 



In this laboratory a series of three periods in a respiration experi- 

 ment is considered perfectly satisfactory if the range in figures for the 

 carbon-dioxide elimination and the oxygen consumption does not 

 exceed 10 c.c. This would be approximately equal to an average 

 deviation of 2.5 per cent for the carbon-dioxide elimination and 2.15 



