318 Professor Marshall Ward, On the Question of 



Table IV. 



Facsimile of a plotting and direct counting of stomata, hairs, 

 ribs, &c, on an area of squared paper representing a little more 

 than one square mm. of leaf surface. 



B. canadensis. Upper surface. 



Sto-mJk OsWraxyis lf-0 , <W //o</lo o<*v*je It /^sy.wn^ 



Explanation of diagram. The vertical lines are a, the margin ; b to e, ribs with 

 distances between. The dots represent the stomata and the crosses the hairs, each 

 in its proper relative position. A square of glass representing exactly 1 sq. mm. 

 was then placed in 5 positions on this area, and the average count taken. 



