THE NATURAL SYSTEM. 119 
being the youngest; the leaves net-veined; the flowers sel- 
dom (or never completely) three-parted; and the sceds two- 
lobed. On the contrary: 
255. The Endogen has its wood, if any, confused, the inner 
portions being the newest ;—its leaves parallel-veined ;—its 
flowers three-parted ; and its seeds ore-lobed. 
LESSON XXXI. 
MORE ABOUT THE NATURAL SYSTEM. 
256. Tous Exogens and Endogens are so clearly defined 
that you may know them as far off as you can see them. 
The next step in the analysis is, to subdivide each of these 
provinces. First, as to the Exogens: We know that they 
generally have pistils in their flowers, with the young seeds 
(ovules) inclosed in their ovaries. But there are exceptions 
to this rule. The Pines, Yews, &c., have no pistils at all, or, 
at least, no stigmas, and produce naked seeds, not inclosed in 
seed-vessels. Hence, we have two classes of Exogens: the 
naked-seeded and the vessel-seeded. The botanists call the lat- 
ter the Anarosprrms (Greek, angzos, a vessel; sperma, seed) ; 
and the former, the Gymnosperms (Greek, gymnos, naked). 
257. Secondly, the Endogens: here consider the peculiar 
forms and flowers of the Grasses. Their flowers are all en- 
veloped in green, alternate scales, called glumes, instead of 
254. Is the Lilyan Exogen or Endogen? The Buttercup? The Maple, &.? 
256. What is the next step in the analysis? State the manner of subdi- 
viding the Exogens. What is the meaning and etymology of the word 
“ Angiosperms ?” What of Gymnosperms? Give an example of each. 
257. Show the subdivision of the Endogens. What of the Petalifere? 
What of the Glumiferz ? 
