INFLUENCE OF LIGHT AND RADIANT HEAL ON TRANSPIRATION. 3/71 
state remaining constant within very narrow limits, gave the following 
result— 
sr sgn of 
ter-vapour. 
After the 1st hour the plant had disengaged 59 
“ 2nd ed 48 
3? 3rd 9 ” 44 
< 4th 3 42 
And the last figure was returned for the next five hou 
The same plant, after eighteen hours’ exposure to o Hight, w 
moved into obscurity, and external conditions remaining ain a 
invariable. 
Milligrammes of 
water-vapour. 
After lapse of 1st hour it had disengaged 31 
‘ 2nd ne 30 
” 
” 3rd bE sake ” 29 
And transpiration grees stationary at the last figure. The result, 
which was support y an experiment with Zea Mais, shows that 
the plant is icatii of only aad placing itself in equilibrium of 
temperature with a new mediu 
Transpiration of green and of sh Pai ace organs im obscurity 
and in light of variable intensity.—The immediately following experi- 
ments show that very green awit are much more sensible to light 
Three young Maize plants with a surface of 31 square centimetres 
and three etiolated ones of 43 square centimetres were compared, and 
the seh between transpiration under diffused light and under direct 
light w. 
In me sree aa as 1 to 39 
tiolated oe 
These figures heing pr mit! by wiaisde till the action is constan 
The difference is, however, more striking if the figures obtained at te 
end of the half-hour are used ; thus the proportion is oa 
With the green ane Lo te 76 
“i etiolated . te oT Ss 
Further experiments with three Maize plants gradually becoming 
mn, and with al ethers kept in obscurity, showed that as the 
organs of the st increased in greenness a greater quantity of 
vapour was transpired, and much more than with the * Diente 
ess. 
Flowers of Spartium junceun having a surinee of 190 square cen- 
«oe rg iar i 
AGS per hour. 
In obscurity . . 123. 
iffused light ‘ 131 
Tn full sunlight 331 
