Notes. 
274 
pounded by Sir Joseph Banks 1 , that the stomata are regulators of 
transpiration, closing when the conditions are such as to promote 
excessive loss of water. 
It is, of course, admitted that the state of the stoma may not in all 
cases entirely depend upon the turgidity or flaccidity of the guard-cells, 
but that it may be affected by the degree of turgidity of the adjacent 
epidermal cells when the anatomical relations are such as to permit 
it 2 . But it may be pointed out that this influence works practically 
in one direction only, that of ensuring the closing of the stomata. For 
instance, in the case of a plant, such as Amaryllis , in which these 
anatomical relations obtain, the effect of a high turgidity in the 
epidermal cells could only be to close the stomata even when the 
guard-cells are highly turgid and tend to separate. A low degree of 
turgidity in the epidermal cells of such a plant would be, in the first 
instance, necessarily accompanied by a low degree of turgidity in the 
guard-cells and closing of the stomata. It is probable that a fall in 
the turgidity of the epidermal cells sufficient to forcibly drag apart the 
guard-cells could only take place in the event of the complete drying- 
up and death of the tissues. 
In conclusion I may point out that this view of the irritability of the 
guard-cells of the stomata is supported by the little that is known as 
to their reaction to other stimuli. Muller observed that induction- 
shocks cause the stomata to close; but not much weight can be 
attached to this, for it appears that these shocks caused the death of 
the guard-cells. More important is the observation of Baranetzky 3 , 
that when a leafy branch is violently shaken, the transpiration is 
momentarily increased, but subsequently diminished, the diminution 
being ascribed to an induced flaccidity of the guard-cells and the 
consequent closure of the stomata. 
S. H. VINES, Oxford. 
1 Sir Joseph Banks, An account of the cause of the disease in corn, Konig and 
Sims’ Annals of Botany, II. 1806. 
2 See also Schaefer, Ueb. den Einfluss des Turgors der Epidermiszellen auf die 
Function des Spaltoeffnungsapparates, Diss. Inaug., Berlin, 1887. 
3 Baranetzky, Botanische Zeitung, 1872. 
