AXD THE DISTRIBUTION OF THE STOMATA. 109 



Stomata. Bemarks. 



Salix baby lonica -^- 



Solanum Dulcamara —7; 



Sopbora japonica ^ Young leaves are n- 



1'8 



Tradescantia vir^inica — r 



The number of species is small ; nevertlioless it comes out 

 fairly clearly that where the under surface is protected against 

 wet the tendency of the stomata to accumulate on the lower 

 surface is stronger than in the class where bloom is absent 

 altogether. 



Fifteen leaves, or 83 per cent., have stomata exclusively on the 



lower surface ; whereas in Class r. only 55 per cent, were in this 



condition. 



It will be seen that in the three leaves that have any 

 stomata above, their number does not exceed one fourth of the 

 whole number of stomata. 



Two leaves may be mentioned in which a coating of hairs on 

 the lower surface serves almost as well as " bloom " to keep the 

 leaf dry during Immersion in water, and in which the stomata are 

 chiefly or exclusively on the lower surface. These are the Rasp- 

 berry and Hydrangea qnercifolia. 



Class g. 

 Leaves whicli have bloom only on the upper surface. 



Stomata, 



2*4 



Convallaria majalis ^ 



38 



Lathyrus pratensis v^ 



Primula Auricula — 



Aft 



Rammculus Flammula — Some leaves have no bloom. 



Trifolium repens -^ 



Vicia Cracca r^ 



V. eativa -^ 



Seven species* : of which one has all its stomata on the upper 



* It was thought fairer to include only one species of Primula and of Tri- 

 foliu?n. 



