108 MK. F. DARWiy ON THE RELATION BETWEEN " BLOOM " 



These results sliow clearly that, in leaves with no bloom on 

 either surface, there is a strong tendency towards accnmulation 

 of stomata in the lower surface. This is also sliowai by the fact 

 that, out of the 137 species, 75 (or 55 per cent.) have no stomata 



on tlie upper surface; that is, in Class ^ (bloom ), tbe group g 

 are 54 per cent. 



Class 5. 

 Leaves with bloom on the lower surface only. 



Here are included a few plants of which the lower surface is of 

 such a character as to come out very dry, though not actually 

 covered with bloom ; such as Cobcea scandens^ Geranium Soberti- 

 anum, Solanum Dulca?naraj&c, 19 species. 



Stomata. Remarts. 



Abies canadensis -., 



A. pectinata g- 



Acer Pseudoplatanus -^ 



Arauja serifera -^ 



Ailanthus glandulosus -^ 



Cassia floribunda -^ 



Oobsea scandens o- 







Daphne Mezereum ~ Young leaves have bloom above. 



Geranium Eobertianum -5- 



Humulus Lupulus..,.. -^ ^^, 



B /This twisted grass-leaf has ita 



[ physically upper side free from 

 Pharus latifolius -^ ^ stomata. (The physically 



upper side is morphologically 



T> 1 i ii-/i I the lower side.)* 



Polygonatum multiuorum -g- ^ ■' 



13 



Primula farinosa ^ Mealy underneath. 



Quercus pedunculata — 



* M. A, de Candolle has been so good as to call my attention to the fact that 

 Juniper, according to Dutrochet (M^moire, ii. p. 100), has stomata only on the 

 upper surfaces of the leaves, and the branches hang down so that the upper 

 surface of the leaves is downwards. 



