drops At the place where the drops appear there are generally found 
peculiar pores; these water-stomata were lirst distinguished by de Baby 
from ordinary stomata. 
It is assumed that the secretion of water is of importance to the 
plant in order to prevent the danger, that water, forced up by root- 
pressure, should become subject to increased pressure m the vascular 
bundles in consequence of impaired transpiration, and shou t us 
be injected into the intercellular spaces. 
Of late years doubt has occasionally arisen whether in all plants 
and under all circumstances this guttation is only to be ascribed 
to the forcing up of the water taken up from the soil hy the roots, 
and whether it is to be regarded as filtration pure and simple. 
In 1895 Haberlandt 1 ) expressed the view that in some plants the 
anatomical structure of the leaf-tooth and especially of the tissue 
between the terminal tracheids of the vascular bundle and the water- 
pores - the so called epithema (be Bary) — suggested a glandular 
function. He also showed experimentally that in Conocephalic* ovatus, 
for instance, this tissue really plays a part in the secretion of water. 
In Fuchsia , however, where the structure of the epithema also very 
strongly suggests a gland, the process was nevertheless found to 
depend in filtration, but here the tissue was supposed to keep the 
system of intercellular spaces between vascular bundles and water- 
cavities filled with water in order to ensure the separation of the 
tracheal system. 
In any case Haberlandt considered the glandular action to e 
dependent on root-pressure; the gland was only supposed to act 
when it was stimulated by the increased pressure of bleeding. 
An investigation by Nestler’) in 1896 clearly showed, however, 
that the phenomenon does not always depend on root-pressuie. 
Nestler found that cut leafy shoots of Tropaeolum majus which 
were kept under a moist bell-jar with their cut surface in water, 
showed after three days drops of water on the younger leaves at 
the termination of the vascular bundles; i. e. in the same place 
where under ordinary circumstances the phenomenon of guttation 
occurs; on the fourth day the formation of drops was also observable 
on some older leaves. 
Nestler remarks in this connexion, that here the epithema cannot 
be concerned in the secretion; in the first place this tissue is not 
9 G. Haberlandt, Ueber wassersecernirende und absorbirende Organe^ Sitzungs- 
berichte der Kais. Akad der Wissensch. in Wien. Abth. II Vol. 104, 189o 
2 ) Nestler, Sitzungsberiebte der Kais. Akad. der Wissenscb. Wir- 
1896. p. 524; Vol. 106. 1897. p. 401. Vol. 108. 1899, p. 690. 
. Vol. 105. 
