BY SELF-ADAPTATION TO THE ENVIRONMENT. 241 
level (Erucaria aleppica). TheseI take to he specially absorbing 
hairs, as well as all which have no wax, or at least places where 
it is wanting. 
As a special peculiarity, I have found in Cocculus Leeba a 
basket-like arrangement of hairs round the axillary buds. This 
would presumably retain a large drop of dew, by means of which 
the bud would be benefited. 
Besides being actual absorbents of dew*, it may be borne in 
mind that not only does the felt collect the dew-drops, which get 
entangled in it and so get absorbed, but it parts with them by 
evaporation much more slowly than does a smooth leaf, as I have 
tested by experiment with many kinds of leaves. 
Now, as Dr. Volkens observes, though suspected, he cannot 
say for certain how or why the hairiness is produced. But, besides, 
the reasonable interpretation of M. Mer which I have given 
above, that hairiness is a direct result of the environment upon 
the plant, is established by numerous cases. In the first place 
we have “ the argument of coincidences,” as I would call it ; but 
when we find that a change of habitat brings about a greater or 
less degree of hairiness, the probabilities accumulate till they 
amount to a moral conviction, which is further established by 
experimental verification. Thus, for example, the hairiness of 
wild plants tends to decrease under cultivation, as in the wild 
parsnip. Linneus observed this fact nearly two hundred years 
ago for he sayst:—“ Spinas et hirsutiem ... plante sepius exuunt 
a loco vel cultura.” Ranunculus repens growing in a dry barren 
gravelly soil is very hairy, but another plant growing in water 
ten feet from the former, which I have preserved, is scarcely 
hairy at all. 
M. Battandier observes + that Bellis atlantica, with leaves 
covered with a true velvet having a long pile, at the summit of 
the mountain Blida, when cultivated in Algeria, bore leaves less 
and less veiv ety till they finally became as glabrousas the Bellis 
of Algeria. 
Similarly Allium Chamemoly, when cultivated for eight years, 
lost its villosity which it had on the summit of Zaccar. So also 
* For proof that plants can absorb rain and dew by their green parts, [ 
would refer the reader to my paper “ On the Absorption of Rain and Dew 
by the Green Parts of Plants,” Journ. Linn. Soc., Bot. xvii. p. 313. 
t Philos. Bot. § 272. 
¢ Bull. Soc, Bot. de Fr. 1887, p. 193. 
