168 On the Transpiration of Plants. [March, 
ought to be made in this case for the less favorable meterologi- __ 
cal conditions during the time this plant was used, as shown by l 
the table. T 
Again, itis very probable that in plants with evergreen leaves 
having thick epidermal tissue evaporation is only possible through 
` the stomata, whereas in the case of leaves which are thin, soft and 
rapidly growing, with little cortical tissue, evaporation is more gen- 
eral from their surfaces. It is quite possible, also, that the number 
of stomata in the case of the Camellia is below the average. How- © 
ever these things may be, the fact remains, that the nature of the 
cuticular tissue of the leaves is hereby shown to be closely re- 
lated to the amount of liquid transpired. = 
This plant exposed during a cloudy and dewy night gained in 
weight to the extent of 310 gr., as shown by the table; the same — 
thing occurred on a rainy night in the house, when the plant was — 
situated about four feet from an open window, as was the casein 
all indoor experiments; the gain in the latter case, as shown by © 
the table, being 230 gr. There was no loss by evaporation at night 
in the open air. : 
Plant No. 6, was a Lantana (Z. carnosa), a shrubby plant, 18 
inches high; leaf surfaée 330 square inches; weight only 1% 
ounces; complete weight fitted for experimentation, 5 pounds 2- 
ounces 250 grains. : 
e following are the results : 
Duration of Loss by | Loss by | Av’ge | Av’ge 
Experiment, | Evapora-| day, |temper-| dew Place. Weather. _ 
tion, | rzhours.| ature. | point 
ee 
I Day nd night/1360 gr./1200 gr.| 66.° | §2.2° |In open airfClear, cloudy. 
II ” 988 | 688 “ | 64. |544 “ Cloudy p 
III “ re e es re ae S Cl’r, windy dewy n't 
I : 
face, this plant evaporated more than any other plants tried, 
ing, in a clear windy day, nearly 2 ounces per square foot of ! 
-~ surface in twelve hours. It will be observed that the Lantana 
_ evaporated nearly three times its own weight in twelve hours. — 
_ A few experiments were made with this plant (as was done with 
_ the Hydrangea) to ascertain how much more rapid the proce 
~ waè about midday than at other periods of the day. Tt was fou 
