SPECIES — GENUS. 27 
48. Again, the former are distinguished for producing seeds 
composed of determinate parts, as cotyledons (§125) and embryo, 
while the latter produce certain minute bodies, called spores, 
having no such distinction of parts. Thus tlle Phenogamia are 
also. called CoryLeponovus and the Cryptogamia AcoTyLEpDo- 
Novs plants. 
49. Lastly, we find in the Phenogamia, a system of com- 
pound organs, such as root, stem, leaf, and flower, successively 
developed on a determinate plan (§18-—26), while in the Cryp- 
togamia, a gradual departure from this plan commences, and 
they become simple expansions of cellular tissue, without sym- 
metry or proportion. 
a. In the following pages we shall first direct our attention exclusively to the 
compound organs of FLoweRiInG Puiants; and since, in our descriptions of these 
organs, frequent references will be made to particular species and genera, for 
illustrations and examples, it seems proper to subjoin, in this place, a brief notice 
of these fundamental divisions also. 
50. A Species embraces all such individuals as may have 
originated from acommon stock. Such individuals bear an es: 
sential resemblance to each other, as well as to their common 
parent, in all their parts. 
a. Thus the white clover, ( Trifolium repens) is a species, embracing thousands 
of contemporary individuals, scattered over our hills and plains, all of a common 
descent, and producing other individuals of their own kind from their seed. The 
innumerable multitudes of individual plants which clothe the earth, are, so far 
as known, comprehended in about 80,000 species. 
151. To this law of resemblance in plants of a common 
origin, there are some apparent exceptions. Individuals from 
the same parent often bear flowers differmg in color, or fruit 
differing in flavor, or leaves differing in form. Such differences 
are called varieties. They are never permanent, but exhibit 
a constant tendency to revert to their original type. 
a. Varieties occur chiefly in cultivated species, as the apple, potatoe, tulip, 
Geranium, &c., occasioned by the different circumstances of soil, climate, and 
culture, to which thev ane subjected. But they continue distinct only until left to 
multiply spontaneousty rrom seed, in their own proper soil. 
62 A Genus is an assemblage of species, with more points 
of agreement than of difference, and more closely resembling 
_ each other than eee any species of other groups. 
