CHAPTER IV. 



TRANSPIRATION. 



Section A. Absorption of water hy transjnring plants. 

 Sectiox B. Loss of weight due to transpiration. 

 Section C. Stomata, Bloom^ Lenticels. 



Section A. Absorption. 



(92) Potometer\ 



In the first series of experiments (Section A) the rate 

 of absorption of water by transpiring plants under varying 

 circumstances is to be observed. This may be done with 

 the potometer shown in fig. 15. Of the three openings of 

 the potometer, A and B are closed by rubber corks ; that 

 in B is perforated by a capillary tube of about 0*3 mm. 

 bore : the tube should just project beyond the cork on the 

 inside and should have a total length of about 20 cm. 

 The end A is closed by an unperforated cork, while to G 

 is fitted about 8 cm. of rubber tubing, of which 4 cm. 

 project beyond the end of the tube. The cork B should 

 first be fitted in, then fill the potometer with water and 



"' F. Darwin andR. Phillips, Cambridge Philosoph. Society, Vol. v. 1886. 



