TRANSPIRATION. 1 1 1 



I. Acid water. 



(a) With nitric acid : 



A Maize-plant | Ditmd t Add ( Q . j 5 p> ct ) Acid ( o - 3 p< ct ) 

 with its roots m J 



lost in 53 hours, ) 

 p. ct. of its weight J 



96-01 105-87 127-10 



(ff) With carbonic acid : 



A Scarlet Runner with its roots in Distilled water Acid water 

 lost in 95^ hours, p. ct. of its weight, 138-22 165*45 



2. Alkaline water. 



(a) With caustic potash : 



A Maize-plant \ Distilled water Alk. (0*02 p. ct.) Alk. (o'i p. ct.) 

 with its roots in J 



lost in 1 18 hours I ,,0-28 94'3 7 2'88 



p. ct. of its weight J 



(ff) With ammonia : 



A Maize-plant with its roots in Distilled water Alkaline (0-2 p. ct.) 

 lost in 43 hours, p. ct. of its weight, 83-25 64-08 



The following figures give a general idea of the results obtained with 

 regard to salts. The plant used was the Maize, and the quantities, as in 

 the preceding table, represent percentages of the Jiving weight of the 

 plant. 



Distilled Mixed salt soln. KNO 3 NH 4 NO, 

 Roots in 



water o-i p. ct. 0*1 p. ct. o-i p. ct. 



Loss due to transpi-1 , 



\ 264-17 247-40 283-20 334*20 



ration in 103 hours J 



The general conclusion to which he comes is that transpiration in- 

 creases with the concentration of the solution of the salt up to a certain 

 point, a point which is reached earlier in the case of alkaline salts and 

 later in the case of acid salts than it is in the case of neutral salts. 

 Beyond this point transpiration diminishes until it becomes equal to that 

 which exists when the roots of the plant are in distilled water, and the 

 transpiration further diminishes with greater concentration. A dilute 

 solution of a mixture of salts causes diminution of transpiration, whilst a 

 solution of the same strength of a single salt increases it. 



Vesque has recently re-investigated this subject, and he 

 comes to the conclusion that the phenomenon in question is 

 one of absorption. He finds that when the plants have been 



