( 308 ) 
well defined in Tropaeolum and secondly drops of water also appear 
on the stem, where I here can be no question whatsoever of epitheuia. 
The secretion there takes place through water-pores which in position 
and shape ditfer more, or less from the ordinary stomata. He believes 
that the explanation of the phenomenon must be sought in osmotic 
forces, which are called into play under the circumstances mentioned, 
and cause the secretion. 
Properly speaking this was not the first time that this phenomenon 
was mentioned. 
As early as 1881 Wilson 1 ) believed he had observed formation 
of drops on the cut branches of Impatiensylandulifera, /. parviflora 
and Fuchsia, but an investigation of Gardiner 8 ) soon showed that, 
as regards Impatiens, there could be no question in Wilson’s experi¬ 
ments of the secretion of water, but of nectar,, whereas in Fuchsia 
the fluid observed by Wilson was not derived from the water-pores 
of the teeth, but was secreted by water-glands in the neighbourhood 
of these pores. 
It is very remarkable that the phenomenon here in question has 
not been observed much earlier, for, as I have found, there are 
undoubtedly numerous plants which, under the above-mentioned 
external conditions, quite independently of root-pressure or artificial 
pressure, show the formation of drops in the clearest manner. I have 
observed this formation for instance in Kerria japonica, Philadelphia 
corfinanus, Weigeha rosea variegata, various species of Spiraea, 
Hydrangea puhescms. Hydrangea campanulata, Deutzia crenata, Cor- 
nus sibirica and in other species of Comus and I am convinced 
that afterwards, in a more detailed treatment of this subject, I shall 
have no difficulty in showing it is the case with many other plants. 
In all these plants clear drops appear after some hours on cut 
ranches under the bell-jar at the tip and margin of young leaves; 
on removal the drops are renewed. 
It will be shown that these drops are formed in definite leaves, 
an that they owe their origin in some cases to mucilage-glands 
which later only secrete water, and in other cases to glands which 
secreted water from the beginning. 
We may s afely assume that in the case of many plants in which 
0 W. P. Wn 
On the 
Leipzig 1881. 
of the excretion of water on the surface of 
F- Leipzig 1881. 
> W : ^ AR!) * N ® R ? On the physiological significance of waterglands and net 
edurgs of the Cambridge Philosoph. Society. Vol. V, p. 34—50. 
