112 



MR. F. DAnwrN ON TITE RELATION BETAVEEiS' '^ BLOOM " 



1st Comparison. 



No stomata above... 

 With stomata above 



Bloom 





 



Bloom 



0^ 



Bloom 



B 

 0" 



Bloom = ^ 



55 per cent 

 45 „ 



83 per cent. 



17 „ 



per cent 

 100 ,. 



38 per cent 



62 ,. 



2ad Comparison. 



Upper stomata equal to 

 or more numerous 

 than lower 



Upper stomata less fre- 

 quent than the lower . 



5 per cent. 



95 ,, 



per cent. 



100 



9f 



71 per cent- 



29 „ 



29 per cent. 



71 „ 



3rd Comparison. 



Stomatal formula J or less 

 Formula greater than ^ . , 



76 per cent. 100 per cent 



24 



*» 







9f 



per cent 

 100 .. 



52 per cent 

 48 „ 



ReynarJcs on the Comparisons. 



Comparing Class — with Class ^, we see that where, as In ^> 



the stomata on the under side of the leaf have the double pro- 

 tection of position and bloom, the percentage of leaves with 

 stomata exclusively on the lower surface is decidedly greater 

 83 per cent, compared with 55 per cent. 



Ti O 



Comparing Class ^ with Class -jr, we find the number of leaves 



having stomata above to be 62 per cent., instead of 45 per cent. 

 That is, more leaves have some stomata above when the upper 

 surface is protected by bloom. But it is remarkable that so 



many (38 per cent.) of Class -^ should have all tlieir stomata 



below*. This may, perhaps, be explained by the fact that bloom 

 is in some cases removed by rain, rubbing of other leaves, &c. ; 

 so that, even where there is bloom above, the lower surface 

 remains the safest position for the stom:ita. Nevertheless, we 



gee that in ^ there are more species with some stomata on the 



upper surface than without any on that surface; whereas in 



Classes -tt and ^ the reverse is the case. 



These leaves seem, on the whole, to be thin delicate leaves; so that one 

 might imagine that stomata on one surface would suffice, and if so, tlie under 

 surface would, as suggested, be the bcsst place. 



