AND ITS EFFECTS UPON ANIMAL LIFE. 



47 



rebreathed before. The direction of the air current through the apparatus is shown by the position 

 of the arrows in the figure. By changing the position of the aspirating flasks, and turning the stop- 

 cocks in the glass tubing inserted through the stoppers closing the upper openings of the aspirators, 

 the current was maintained in the same direction as before, and the entrance of external air was 

 thereby |)revented. 



The results obtained show that, with the absorption of the COj as generated, the mouse re- 

 mained relatively comfortable in the atmosphere present and that no deleterious effects developed 

 from the continued rebrcathing of the air confined within the apparatus. The animal seemed to 

 be somewhat oppressed toward the close of each experiment, but revived quickly after removal 

 from the apparatus. 



The air contained in the two aspirating flasks was retained each time in the later experiments. 

 Consequently in these experiments the fresh air-supply comprised only that which was enclo.sed in 

 the Pettenkofer tubes, the rubber connecting tubes, and in the hell-jar containing the animal. In 

 several of the later experiments the volume of air within the apparatus was aspirated continuously 

 through all its parts for some hours before beginning the experiment. In this manner the pure 

 air-supply was reduced to one litre, the amount of air in the bell-jar containing the animal. 



V. — Experiments to determine the proportions of C0„ and of O in the air of a glass vessel in 

 which small animals (mice and birds) had remained until death was produced, and the effects of 

 different temperatures upon the duration of life and on the composition of the residual atmosphere 

 after death in such cases. 



The results obtained in these experiments are shown in Table I. At the room temperature 

 death did not take place until the amount of oxygen present was too low to support life. At a 

 higher or lower temperature there was a slightly shorter duration of life, varying with the amount 

 of increase or reduction of the temperature. 



T.-^BLE I. 

 EXPERIMENTS WITH .\NIMAI,S IN CLOSED VESSELS— ATMOSPHERIC AIR. 



