only practical difference being that when specimens are placed in 

 the bulb their volume has to be determined ; in other words, the 

 capacity of the burette has to be reestimated. This is done by 

 filling the burette and measuring the contents with another 

 burette or pipette. The principal feature of the apparatus con- 

 sists in having the specimens in the burette that is employed in 

 making the determination. For experimental purposes we gener- 



Fl'i. I. Ajiparatu.^ f(ji(letcrmiiiiii(^ the amtmnt of carbon dioxide taken 

 up hy plant tissues. 



ally select Myriophylliiiii Icaxcs and have about 5 or 10 per cent. 

 of carbon dioxide in the burette. The method of operation is as 

 ff)llow.s : The required amount of carbon dioxide is supplied to the 

 burette containing the plants by first filling with water or mer- 



