RELATION OF TRANSPIRATION TO STOMATA 489 
and then determine what relation, if any, exists between the amount 
of water lost and the amount of stomatal aperture in linear units, 
per unit of leaf area. 
II. Method 
Various methods have been devised and employed for the quanti- 
tative determination of transpiration both directly and indirectly. 
It seems that the results, in order to be of much value, should be 
obtained from plants which at least approach the natural conditions 
of the plant. Some investigators have confined their investigations 
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0 
= ROOTED PLR/fTS 
Fig. I. Showing the amount of transpiration in mg. per hour per sq. dc. leaf 
surface for cuttings anj rooted plants of the several species. 
entirely to observations upon removed parts of plants, small cuttings 
of branches, or even single leaves. Lloyd (10) worked only with 
cuttings in his experiments on stomatal movements. Freeman (6) 
questions the value of determinations of water loss made from detached 
parts of plants except where only comparative results are desired, 
which was the case in Lloyd's work (10). However, it is doubtful 
whether the limited number of experiments performed by Freeman (6) 
