462 POPULAR BOTANY. 
moisture therefrom that the albumen or amylum becomes liquid, and in 
this state they serve as the nourishment for the embryo. Starting into 
life, the embryo gradually gains in size, presses on the cotyledons, and 
these again on the coat, until they burst, even if they were the hardest 
nut shells ! 
The embryo begins thereafter to extend downward, forming the roots, 
and as soon as this penetrates the ground and is able to absorb nourish- 
ment from them, it supports the germ, which grows now upward, 
forming, in true time, "the stem, leaves, branches, twigs, flowers and 
fruits. 
What next will take us with surprise is the extraordinary diversity in 
the vegetable world. This is not less remarkable between the different 
kinds of plants, than between their parts. 
Although the number of native plants, Cryptogams and Algae 
included, may be estimated at about 200,000 species ; nevertheless it is 
a rare case, to find two species, whose leaves are entirely of the same 
form. , 
The correct knowledge and description of all these forms can only 
be regarded as one of the most difficult tasks in the study of botany. 
It is called the terminology of plants ; and fills many immense volumes 
with expressions, mostly derived from foreign languages. 
For its monotony the terminology of plants may be regarded as the 
very touchstone for the earnestness and perseverance of young botanists 
and, in most instances, it becomes the rock where both may be 
wrecked. ! 
Another very interesting quality of plants is the great diversity 
in their colours. The most prevailing is green, which colour is 
most pleasing and beneficial to the eye. Then follow white, yellow, 
red, and blue, with all the imaginable mixed colours, shades and 
nuances. The brilliancy of flower colours excels all that is found else- 
where. 
It happens, not unfrequently, that the most brilliant colours in the 
most striking contrasts and in the most regular design are found in the 
small space of a petal of a more regular construction than the best artist 
would be able to produce. 
Next to colours, the fragrance of many vegetables must be regarded 
as of great interest and value. In their delicate organism they 
frequently prepare fluids and gases which transpire through the leaves, 
flowers, and fruits, and produce that kind of sensation to the olfactory 
nerve which we call the smell. This odour is very agreeable in many 
cases, but often, however, it is the direct opposite and even dangerous. 
The aromatic plants, or their parts, are frequently used for different 
purposes, as for perfumery, spices, medicines, &c. ; in many cases, how- 
ever, the essential constituents are extracted from them in the shape of 
extracts, tinctures, ethereal oil, &c. 
