Dixon — On the Effects of Gases on Transpiration. 621 



observations it is hoped that, at least, an approximation to the actual 

 alteration in the rate of transpiration has been obtained. The numbers 

 here given are the means of a large number of observations. In each 

 case, the branches experimented on were from a tree of Syringa 

 vulgaris, except in the last set of experiments, where effect of ether 

 vapour was observed. In these last, branches of Cytisus laburnum 

 were used. 



Table I. 



No. of 

 Observations. 



Medium. 



Temperature. 



Amount transpired 

 in 30'. 



20 



I Oxygen, . 



(Air, . . . 



18-2° 

 18-2° 



•140 grs. 

 •103 grs. 



15 



JCO2, . . . 

 (Air, . . . 



15-8° 

 ' 15-7° 



•103 grs. 

 •118 grs. 



10 



i Chloroform, 



( Air, .... 



20-5 

 20-8 



•077 grs. 

 •116 grs. 



10 



i Ether, 



( Air, . . . . 



19-1 

 19-0 



•237 grs. 

 •283 grs. 



If the amount transpired in air be taken as 100, the amounts 

 transpired in the other gases are as follows. This may be said to 

 denote to the specific transpiration for these gases : — 



Table II. 



Medium. 



Specific 

 Transpiration. 



Oxygen, 



Air, .... 



CO2, .... 



Ether, .... 

 Chloroform, 



135-8 



100-0 



87^3 



82-3 



66-4 



The first source of error effecting these experiments, aud one 



E.I. A. PKOC, SEE. III., VOL. IV. 2 T 



