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A GLIMPSE OF THE LIFE OF CHLOROPHYLLOUS PLANTS. 83 
young plant to consume, and this holds good for bulbs and 
tubers. Here the plantlets lead a parasitic life which is 
characteristic of all plants devoid of chlorophyll; they live 
on organic matter already formed. In the case of plants 
grown from seed, if they are kept in the dark, growth con- 
tinues for some time—a short time—after the reserve material 
of the seed is consumed, provided moisture, air, heat, and 
nourishment are present. 
What is it that light does for plants which are exposed 
to it, under suitable atmospheric conditions, which enables 
them to grow to maturity? Through the influence of light, 
of more or less intensity, plants are enabled to manufacture 
in their leaves a green coloured substance known as chlor- 
ophyll. It is to plants which possess this power that I 
purpose drawing attention. Generally speaking, they are 
composed of roots, stems, and leaves, and are re-produced— 
there are exceptions—by seeds, bulbs, and tubers. 
Some seeds will germinate only when quite fresh; others, 
as those of the grasses, and seeds containing starch, may 
be kept dry, and will retain their power of germination for 
years. It is, however, essential for the germination of all 
seeds that the temperature does not vary between certain 
limits, and these limits, upper and lower, are not the same 
for all seeds, 
The radicle, or young root, first emerges from the seed, 
and after it the plumule. The plumule in monocotyledons 
consists of superimposed leaves of a sheath-like character 
while in dicotyledons, when the cotyledons separate, they 
are green and leaf-like. 
What are the faculties belonging to the internal structure 
of a plant, and what influence have external surroundings 
on these faculties by which the plant is enabled to grow? 
The circulation of blood in animals can be easily shewn, and 
this can also be demonstrated for some of the lower plants. 
I think that Professor Huxley’s description of the circula- 
tion of protoplasm in the hairs of the common nettle 
