THE NATURAL SYSTEM. 11U 



being the youngest ; the leaves net-veined ; the flowers sel- 

 dom (or never completely) three-parted; and the seeds 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 or.e-lobed. 



LESSON XXXI. 



MORE ABOUT THE NATURAL SYSTEM. 



256. THUS 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 ANGIOSPERMS (Greek, angios, a vessel ; sperma, seed) ; 

 and the former, the GYMNOSPERMS (Greek, gyrnnos, 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 Lily an Exogen or Endogen? The Buttercup? The Maple, &c. 1 



256. Wliat is the next step in the analysis ? State the manner of subdi- 

 viding th3 Exogens. What is the meaning and etymology of the word 

 ' Angiosperms f What of Gymnosperms ? Give an example of each. 



257. Show the subdivision of the Endogens. What of the Petaliferse ! 

 What of the Glumifene ? 



