PRINCIPLES OF CLASSIFICATION, 121 
of Part I., and comparing them together. Suppose, for 
example, we take the buttercup, sweet-pea, and primrose 
(though almost any others will do just as well), and observe 
first of all the venation of the leaves—it is netted. Now 
compare these with the iris, lily, and oat (or other plants 
like these): the venation is straight. This is no mere coin- 
cidence ; but we shall compare further: let us look at the 
flowers. The buttercup has 5 sepals, 5 petals, co stamens, 
and co carpels; the sweet-pea has 5 sepals, 5 petals, 10 
stamens, and 1 carpel; and the primrose has 5 sepals, 5 petals, 
5 stamens, and 5 carpels. The number 5 seems to be promi- 
nent among them; while if, instead of these, you had taken 
the wallflower or the fuchsia, you would have found 4 or 2 to 
be the prevailing number. On the other hand, in iris you find 
6 perlanth-leaves (= 8 sepals and 3 petals), 8 stamens, and 3 
carpels; in lily 6 perianth-leaves, 6 stamens, and 8 carpels; 
while in the oat the perianth-leaves are reduced to 2, but there 
are 3 stamens and (1 carpel with) 3 styles. Here the number 3 
prevails, and this will be found to be equally the case if you 
take other plants allied to those named. Let us carry this 
comparison further. Examine the seeds of the pea (or of the 
cabbage, &c.), and you-find two cotyledons, or seed-leaves, 
and, though you cannot see these in the seeds of the butter- 
cup and primrose, yet if you watch those seeds springing in 
the soil you will observe that as soon as they come above 
ground the young plants always exhibit two seed-leaves. 
Similarly observe the springing of any iris-, lily-, or oat-seed, 
and you will only observe one cotyledon coming up. | 
Now, the structure and characters of the reproductive 
organs are not so likely to alter under any change of circum- 
stances as are the habit of the plant, the form of its leaves, 
sepals, petals, and other external parts, and therefore the 
former, though less conspicuous than the latter, have always 
been considered the most important features in classification. 
Recognising this fact, Antoine de Jussieu, a celebrated French 
botanist, and the chief founder of this system, divided all 
flowering plants into two great classes, called respectively after 
their most important characters, Dicotyledons and Mono- 
cotyledons; and all our more recent knowledge only tends 
to confirm the view that these two represent the two great 
primary natural divisions. You will find that the following 
characters as a rule are shown by the plants belonging to 
these classes :— 
(a). Dicotyledons have— 
(1.) Two seed-leayes. 
2.) Netted-veined leaves. 
(3.) Parts of the flower in 2s or 5s. 
