[Vor. 5, 1918] 
174 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
at least some continuous water channels established by means 
of the open water-suffused stomata. Under such conditions 
it seems fair to assume that the water would spread through 
the film of Bordeaux mixture, and the evaporating surface 
would thereby be greatly inereased. On the other hand, dur- 
ing the day, as this state of incipient guttation might give 
way to a condition in which the interchange between the in- 
ner and outer atmosphere is governed wholly by the diffusion 
of water vapor, the presence of an absorbent surface film 
would have little, or at least far less, power to increase the 
evaporating surface, or in any other known manner to facili- 
tate evaporation. 
Again, taking the case of Cyperus, an explanation of the 
failure of the surface film to inerease the transpiration rate 
might then be found both in the fact that the stomatal open- 
ings are exceedingly small, and that the air space of the leaf 
tissue is very limited in extent. In all probability, with such 
material, a state approaching guttation would be realized 
with great difficulty, if at all, and a ‘‘clogging”’ of the stomata 
might indeed tend to inhibit transpiration. 
The excised leaves which are able to maintain themselves 
at all might be expected to exhibit very different water rela- 
tions, and it is not possible from the data at hand to conclude 
that in this case there is in reality any possibility of a state 
of incipient guttation. This is, however, possible. At any 
rate, the writers have found no satisfactory explanation of 
the results obtained except the one just discussed. Some 
phases of this explanation are susceptible of direct experi- 
mentation and in further work it is proposed to subject the 
matter to critical test. For the present it is offered as a sug- 
gestion merely. 
Graduate Laboratory, Missouri Botanical Garden. 
