17 



period than that mentioned in the preceding section. Such 

 a detrimental influence would render the results of our 

 further experiments somewhat uncertain. 



Ànyhow in the first place constancy of velocity of assi- 

 milation under unaltered circumstances at a harmless tem- 

 pérature should be required, else the experiments would 

 not be rehable. In order to establish this, some Helodea- 

 shoots were exposed during 1 hour at 24° C. to the 

 light of 2482 candies, the water being collected in a 

 continuous séries of flasks. The fiUing of one flask took 

 about 4V2 à 5 minutes. 



On the whole 10 flasks were filled, the first one with 

 water that had not streamed along the shoots. Table III 

 shows the results of this experiment. 



Table III. 

 The rate of assimilation when the circum- 

 stances are constant (24° C, 2482 candies). 



^) Water collected directiy. 



Recueil des trav. bot. Néerl. Vol. XIII. 1916. 



