NUTRITION, STORAGE, AND RESPIRATION 



103 



It may be shown that the volume of carbon dioxide absorbed is 

 approximately equal to the volume of oxygen given off in Photo- 

 Synthesis by the use of Hofmann's apparatus (Fig. 76). It consists 

 of a tube shaped like a horse-shoe, with one side closed, the other 



FIG. 75- 



Arrangements for experiment of Timiriazeff to show that 

 the decomposition of carbon-dioxide takes place at the ex- 

 pense of the rays absorbed. See Text. (After Timiriazeff.) 



FIG. 76. 



Hofmann's apparatus. 

 (After Timiriazeff.) See 

 Text. 



fitted with a stopper. The whole tube is first filled with water. 

 Carbon dioxide is then passed into the left-hand side of the curved 

 tube which is closed, so as to fill it to a certain marked point. A 

 green leaf is then passed into the right hand side of the tube, and its 

 end is also closed ; the whole apparatus is then exposed to sunlight. 

 Gas will be evolved in the right limb, and the level of the fluid will 



