OBSERVATIONS FOR YOUNG BOTANISTS 207 
barleys, grapes, melons, pansies, sweet-peas, chrysanthemums, 
li'C. Similarly in the animal kingdom, all the domesticated 
pigeons are derived from the wild blue rock pigeon : all our 
horses and ponies are derived from one kind ; and similarly is it 
with the numerous breeds of sheep and oxen. 
The next question is, what induces plants to change at all ? 
When we look at blue-bells, heath, daisies, buttercups, marsh- 
marigolds and many other plants which grow in masses, we 
perceive no changes year after year. They remain the same in 
the wild state. If, however, they be cultivated, as the daisy 
and pansy have been, we know that the garden forms have 
become very different from the wild ones. We therefore 
conclude that a change of -soil is one thing and a change of 
climate an additional aid. 
Some experiments have well illustrated this fact. In arctic 
regions and in high alpine places, plants are dwarfed and have 
often very brilliantly coloured flowers. They possess, also, 
several other features, such as a dense woolly clothing in some 
cases, as in the familiar edelweiss. Now, such plants when 
cultivated in lowland regions often change very much — they 
grow tall, lose a good deal of their hair, and the minute structure 
of their foliage alters. Conversely, if plants usually growing 
in lowlands are planted on high mountain regions or within 
the arctic circle, they acquire the peculiarities of the native 
vegetation. 
-\gain, if we examine aquatic flowering plants, they all have 
certain features in common, such as air-chambers in the stems 
and petioles, and the blades of the leaves are in many cases finel}' 
divided up, as in the water crowfoots, Myriophyllum, and water 
violet [Hottonia palustris). One is driven irresistibly to the con- 
clusion that these and other peculiarities are simply the result of 
an aquatic life. 
To take an opposite condition : in hot and arid deserts, as 
around Cairo, all sorts of plants have small leaves, rolled-up, 
densely hairy and covered with a waxy epidermis — provisions for 
preventing a loss of water during the greater part of the year 
when no rain falls. Another form is a fleshy, leafless stem with 
a thick skin, so that much water can be stored up ; this occurs 
in Cactuses, Euphorbias and many other plants. As such 
features occur in plants of the deserts of America, Africa and 
Asia, we are again driven to the conclusion that such admirable 
adaptations to the conditions of life are simply the result of the 
powers of self-adaptation to its surroundings possessed by the 
plant itself. The final outcome are various structures which 
systematic botanists regard as “ specific,” “ generic,” or other- 
wise. All the above observations apply to the vegetative organs 
of plants — roots, stems and leaves. 
We have already seen how the various forms of flowers 
appear to be adapted either to insect-, wind-, or self-fertilisa- 
tion ; and these adaptations have never come into existence, so 
