1894.] Absorption of Water by Green Parts. 137 
that the soil has become dry, and if the soil be protected, it 
will not revive at all when sprayed and kept in a damp at- 
mosphere. The explanation of these facts seems to be that 
the rate of supply of water to leaves by conduction from roots 
has a maximum which may be exceeded under the same con- 
ditions by the rate of loss through transpiration, and when 
this occurs drooping follows. To plants in this condition 
spraying, when it does not directly water the earth, 
creates a moist atmosphere which is for some time main- 
tained by evaporation of the clinging water-drops; trans- 
Piration is thereby diminished until it is equalled and ex- 
ceeded by conduction, and revival follows. But when the 
drooping is the result of absence of water at the roots, these 
being protected no revival can follow the spraying except by 
direct absorption through the green parts; and the fact that in 
such cases no revival takes place is fair evidence that absorp- 
tion through the green parts cannot, to any appreciably pro- 
fitable extent, occur. That the revival of drooping parts can 
eet follow simple diminution of too rapid transpiration 
of re addition of water, is shown upon a large scale out 
Pe a in gardens when hot summer days are followed by 
a ag and still better, in the irrigated regions of the 
sees wi . of which cases there is an evening revival of 
day, ich drooped under the heat and brightness of the 
So mu 
has b 
tance 
the id 
Wishin 
does Sita, upon cut plants, concluding that absorp- 
Henslow had t ace through green parts. In the meantime 
With similar fen carrying on independently similar studies 
Were publish fy €ven more positive conclusions, and these 
Physiolo shed shortly after.? Sachs in his ‘‘Lectures on the 
8y of Plants”* gives his opinion that the ‘‘numerous 
sino malar 
Bal ; 
2 rg ior Eot de France, 4:—.—. 
: Age “yr et de Physique. March, 1878. 
Ed. p, sed (Bot.) 17:313-327. 1879. 
