^8 WRIGHT : FOLIAR PERIODICITY 
others. This plant possesses thick stiff leaves (which are pro¬ 
tected by a strong thick cuticle and a layer of cells running 
under the epidermis on the upper surface of the leaf) and 
narrow stomata. He proved that the transpiration from 
one plant of this species was, from the 23rd to the 27th 
January, both days inclusive, only 0-457 gram, or at the rate 
of about one gram in ten days. This means approximately 
one pound of water in 13 years, a very small quantity indeed. 
Alstoma scholaris was also experimented with. The 
eaves of this commonly occurring tree are not xerophytic ; 
they possess normal stomata andinternal tissues, anda cuticle 
of average thickness. One shrub of this plant possessing 100 
leaves lost during the 13th and 14th February, when the 
sky was cloudless and the temperature high, 1-24 gram ; 
ut during the 15th and 16th when rain was falling only 
0 06 gram of moisture was lost by transpiration. Discus¬ 
sing the value of these and other observations Holtermann 
proceeds to state that there is between 12 and 2 o’clock on 
clear days in the tropics a much greater loss of water by 
T ! in Eur ° pe ’ th0Ugh the total transpiration 
tropical plant in 24 hours may be less than in Europe. 
There are in the tropics a large number of plants which 
ough exposed to the full rays of the sun only lose a small 
quantity of moisture by transpiration; ^. EupVoXa 
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