X li ANALYSIS OF THE LESSONS. 



LESSON Xn. SILICA, CONTINUED, P- 36. 



216. Silica abounds in the lowest plants. 217. The loricaB of the Diatoms. 

 218. The Arachmoidiscus. 219. Recent and fossil Diatomaceae. 220. Silica in 

 the grasses. 221. How it is that straw grows erect. 222. How to demonstrate 

 its structure. 223. Defence of the grasses : husk of Rye. 224. Husks, and 

 pale of grasses : effects of brown bread. 225. Demonstration of this state 

 ment. 226. By means of the microscope. 227. The action of silica on the 

 organs of nutrition. 228. The Berg-mehl. 229. Its microscopical character. 



LESSON Xm. SILICA, CONCLUDED, , , p. 38. 



230. Silica from the husk of the Oat. 231. From the husk of the Rice. 

 232. Flint in the Horse tails. 233. The flint a cast of the cuticle. 234. Struc- 

 ture of the Stomata. 235. The uses of Dutch rush. 236. The bullrushes. 

 237. Silica not confined to the grasses. 238. The Deutzia scabra. 239. The 

 structure of the upper cuticle. 240. The under cuticle. 241. Use of the leaves 

 of Deutzia. 242. Large amount of silica in the canes. 243. The like in reeds. 

 244. The formation of vegetable sap. 245. Mutual decomposition of some oi 

 the elements. 246. The silicic acid of Chara translucens, and allied species. 



LESSON XIV. HAIRS, p. 41. 



247. Composition of hairs. 248. Variety of their form. 249. How consti- 

 tuted. 250. Where found. 251. They are sometimes very extensively de- 

 veloped. 252. Hairs of the Cowitch. 253. Of Venus' Fly-trap. 254. Hairs 

 of Cotton. 255. The division of hairs. 256. Glandular hairs. 257. Stalked 

 hairs. 258. Hairs are sometimes ducts. 259. Hair of the nettle. 260. How 

 to avoid being stung by it. 261. Hair of Chinese sundew. 



LESSON XV. CUTICLE, p. 44. 



262. Resemblance between the cuticle of plants and animals. 263. Mode of 

 its formation in plants. 264. Its texture. 265. Position of the stomata. 266. 

 Opening and closing of the stomata : on what this action depends. 267. The 

 number of stomata. 268. Number in different plants tabulated. 269. Leaves 

 upon which stomata are not found. 270. Stomata of Ruscus aculeatus. 271. 

 Of the Ivy. 272. Of the White Lily. 



LESSON XVI. LEAVES, . . . ; ,,.'... V p. 46. 



273. Nature of leaves: their varieties. 274. AERIAL LEAVES description 

 of them. 275. Vascular system of the leaf. 276. How distributed. 277. The 

 Parenchyma. 278. How formed. 279. The upper cells of the Parenchyma. 

 280. Examination of a Melon leaf. 281. Of the leaf of the Balsam. 282. The 

 green color of leaves. 283. The dark color of the Negro skin : how caused. 

 284. The same law governs the color of the leaf of a plant and the human 

 skin. 285. The vascular system of a leaf. 



LESSON XVII OP THE STEMS OF TREES, p. 48. 



286. Their anatomical character. 287. Of what the stems are composed. 



