TRANSPIRATION. 



The following figures refer to Baranetzky's experiments with a leafy 

 stem of Inula Helenium cut off and placed in water : 



The following table refers to experiments made with a branch of 

 Hippocastanum. 



We have now considered in detail the influence of 

 external conditions upon the process of transpiration, and we 

 may proceed to enquire if there is an independent periodicity 

 of .transpiration as there is of root-pressure. It is probable 

 a priori that such is the case, for as we have already seen, the 

 root-pressure exhibits a periodicity, and, as we shall see here- 

 after, the tension of the tissues exhibits it also : but, when 

 it is borne in mind how many are the external influences 

 which affect this process and how readily it responds to 

 their action, it will be seen that the difficulties in the way 

 v. 8 



