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ANNIVERSARY ADDRESS 
old leaves when subjected to cold at night. The feebleness of 
youth in this way protects itself by a configuration similar to that 
which low temperature produces. In fact the position of many 
leaves at night is a kindred protection against temperature with the 
resinous covering of many buds. 
It is scarcely necessary for me to do more than allude to the 
various means of protection which many flowers possess against the 
visits of winged insects which are not likely to cause their fertili¬ 
sation. 
Protection' by means of Mimicry. 
I use the word mimicry, not only for want of a better, but 
because it has been generally applied to the phenomena of which I 
am about to treat. All that is implied by the expression in such 
cases is that one object is so like another that an observer cannot 
distinguish the two without critical examination. It is clear that 
if an unprotected plant should resemble one that is protected, or 
some inedible substance, it might be passed over by its enemies. I 
cannot state that I have seen an instance of an animal apparently 
avoiding a plant from any resemblance to other objects that it may 
possess, but I will mention a few cases of mimicry which might 
well be supposed to lead to such an occurrence. Many plants in 
the Karoo have exposed tuberous roots which resemble so much the 
surrounding stones, that when not in leaf it is almost impossible to 
distinguish them.* The dead-nettle is exceedingly like the com¬ 
mon stinging-nettle, and, when the two plants are not in flower, it 
is very difficult to distinguish the one from the other. The latter 
is, as I have already stated, avoided by many animals. The wood- 
ranunculus {Ranunculus auricomus ), which is less unpalatable than 
many buttercups, as its pre-Linnean name dulcis denotes, may be 
protected from its resemblance to the common meadow-ranunculus 
( R . acris ), which, as its botanical name implies, is acrid. The Poa 
pratensis or smooth meadow-grass is easily mistaken for the Poa 
trivialis or rough meadow-grass, so much so that, when in flower, 
experienced botanists frequently run the stalk through their fingers 
before naming the species. The young leaves of both grasses 
appear to be liked by grazing animals, but the many standing 
stalks of the rough meadow-grass show that its texture is recog¬ 
nised, and the stalk of the smooth meadow-grass may be preserved 
by its similarity of appearance. A more interesting case of mimicry 
occurs between the potentils and the buttercups, which frequently 
grow together. The resemblance is noteworthy, for the potentils 
* See Wallace’s ‘Tropical Nature,’ p. 223. 
