92 



A MONTANE RAIN-FOEEST. 



acter of foliage, and were placed alongside them during the intervals 

 between weighings. I am unable to say in how far the results which I 

 am about to give have been modified by the limitations of the methods 

 used. The fact, however, that all of the evidence which I have secured 

 for four species of plants fails to show any serious discordance leads 

 me to believe that the plants used for transpiration and those used 

 for stomata did not behave in such a dissimilar manner as to destroy 

 the validity of my conclusions. 



In making measurements of stomatal aperture from the stained and 

 mounted pieces of epidermis, by means of a micrometer eye-piece, I 

 commonly took readings from 24 stomata in each preparation. UnUke 

 other workers who have used this method I did not discard the extreme 

 readings, nor fail to measure the most divergent stomata observed, but 

 measured all stomata throughout a path across the piece of epidernais. 



A considerable degree of variabiUty was disclosed in the openness 

 of the stomata in nearly all of the preparations of epidermis. The 

 variability of diameter in two plants, Peperomia turfosa and Diplazium 

 celtidifoUum, is indicated by the data in table 35. Peperomia exhibits 

 its widest variabiUty at the first two morning readings, and shows 

 considerable constancy at noon, again becoming variable in the after- 

 noon. Diplazium shows a less range of variability, as well as a more 

 constant diameter throughout the day. These are given as typical 

 cases of stomatal variabiUty and they have been treated, as have all 

 other sets of readings, as the normal behavior of the plants concerned, 



Table 35. — YariabilUy of stomatal diameter in Peperomia turfosa and Diplazium celtidifoUum, 



October 16, 1909. 



