416 



Dr. J. B. Farmer and Mr. S. E. Chandler. [May 6, 



As regards the structure of the leaf, the character of the mesophyll 

 does not differ, except in amount, in the two cases. 



The roots showed no difference whatever in structure in the two 

 series. 



FlG-. 2. Kalanchoe WelioitscMi, transverse section of the stem. A, air- ; 

 B, C0 2 -plant. 



Kalanchoe stands alone amongst the plants we examined in one 

 respect. The specimens which had been exposed to the additional 

 carbon dioxide exhibited no increase in the amount of starch present 

 in their leaves or cauline parenchyma. But a difference was indicated 

 between the metabolic proceeds of the C0 2 and air plants respectively 

 in two other particulars. Firstly, the air plants contained large 

 quantities of tannin-cells, especially in the vicinity of the vascular 

 bundles. These were very much fewer and far less striking in the C0 2 

 plant. Again, the air plants possessed crystal-containing cells of 

 remarkable form in the pith. These occur in groups, each group 

 having arisen by the division of a single mother cell, the limits of 

 which can still be traced. Each cell thus produced contains crystals 

 of calcium oxalate. These special cell groups were entirely absent 

 from the CO2 plants ; and when crystals occur in them, as they do 

 very occasionally, they are found in ordinary unspecialised cells of the 

 ground tissue. 



Solatium airojourpureum, — The general tendency towards a stunted 



