! EXCHANGE OF MATEEIAL 



the place of N as soon as the latter is empty) by the water coming from the 

 ctte?n in which it is always kept at a constant level, /efore enter ng th 

 hpll inr the oxv^en passes through the filtering bottle M. Ihe 

 ^fo^S^tlHS-jarc^municateB on the one hand with a mercurial 

 Sale showing the gaseous pressure prevailing m the interior of 

 tie system and on tTe other hfnd with a U-shaped tube containing mercury 

 I" d] wldch Serves for the removal of samples of air from the bell-jar. 

 ( If we determine the composition of the air in the bell-jar before and 

 after the experiment, the quantities of carbon dioxide discharged and 

 nlvLrLorbedTuring the Experiment, it is obvious that we can by this 

 d dly ascertain the gaseous respiratory exchange of a smaU animal 

 rW the period of several hours spent by it in the apparatus 

 One of the drawbacks of this method is that the animal is forced to 



Fic; ] Apparatus of Regnault aud Keiset. 





VOL. V 



