ANALYSIS OF THE LESSONS. XI 



tity in English as compared with Turkey Khubarb. 139. Stellate crystals, where 

 found. 140. Other acids found in plants. 141. Phosphate of Lime. 142. The 

 number of raphides found in a given space. 143. Their number in the Cacti. 

 144. Bark of trees contains them. 145. And the testa of certain seeds. 



LESSON VIII. SCLEROGEN, OR LlGNINE, p. 24. 



146. Definition of the name. 147. Sclerogen of Nut Ivory. 148. Originally 

 soft. 149. Demonstration of it. 150. Gritty tissue. 161. A Pear demon- 

 strated. 152. Probable intention of this structure. 153. Demonstration of this 

 tissue, repeated. 154. Sclerogen in testa of Nut Ivory. 165. The Sclerogen of 

 fruit stones described. 156. The Cherry stone demonstrated. 157. The Cocoa- 

 nut shell. 158. Importance of wood and bass-cells. 159. Bass-cells described. 

 160. The uses to which they are applied. 161. Flax, Hemp, &c., where pro- 

 cured. 162. Other plants described. 163. Tenacity of woody fibre, tabulated. 

 164. The fibre preserved in Chinese rice paper. 165. Necessity of examining 

 Flax, microscopically. 166. How to proceed. 167. What will be seen. 168. 

 The outer membrane. 169. Length of tubes. 170. Cotton not woody fibre. 



LESSON IX. VASCULAR TISSUE, p. 28. 



171. Action of the roots of a plant. 172. Effects of the motion of the sap. 

 173. Formation of vascular tissue. 174. Vascular tissue in Monocotyledonous 

 plants. 175. In Dicotyledonous plants. 176. Development of wood. 177. 

 Value of the spiral fibre. 178. Vascular tissue under the microscope. 179. The 

 several forms of vessels. 180. The original form of spiral vessels. 181. Disin- 

 tegration of spiral vessels. 182. The process of decay. 183. Absorption does 

 not cease. 184. The mode in which an annulus divides. 185. Formation of 

 " old vessels." 186. The shape of vessels. 187. Scalariform vessels. 



LESSON X. POROUS AND DOTTED DUCTS, p. 32. 



188. Description of ducts. 189. Distinction between spiral vessels and ducts. 

 190. The trees they are peculiar to. 191. A description of the cells. 192. 

 Dotted ducts of the Pines, described. 193. Value of their characters. 194. 

 Shape of the dotted or porous vessels. 195. The perforations of old dotted 

 ducts. 196. They are often jointed. 197. Where found : their appearance. 

 198. Porous ducts of the Locust tree. 199. Same in the Apple tree. 200. And 

 in the Bass-wood. 201. Description of it. 



LESSON XI. SILICA, p. 34. 



202. Its importance to the plant. 203. Necessity for Carbonate of lime. 

 204. How it is compounded. 205. Silica exists in plants as pure flint. 206. How 

 it is obtained. 207. Grasses contain silica in large quantity. 208. The method 

 of digesting it. 209. Silica succumbs to alkalies. 210. The silicates formed by 

 the Chemist. 211. Properties of the natural silicates. 212. This subject con- 

 tinued. 213. The probable process of silicification of plants and animals. 214. 

 Continued. 215. Artificial fossilization, or silicification. 



