Xviii LIST OF ILLUSTRATIONS 



FIG. PAGE 



180 Potato showing the effect of light and dryness on growth 328 



181 Sprout of Prickly Pear grown in the dark 329 



182 A spherical Cactus 331 



183 Branch of Cytisus 332 



184 Stems of Callitriche in cross-section 333 



185 Epidermis of Holly 334 



186 Waxy covering of Sugar Cane 334 



187 Hairs of Wormwood or Sage Brush 334 



188 Hairs of Mullein 335 



189 Cross-section of stem of Water-polygonum grown in dry soil 335 



190 Cross-section of stem of Water-polygonum grown in water 335 



191 Upper epidermis of Water-polygonum 336 



1 92 Cross-section of a leaf of Oleander 337 



193 Arrowhead, showing effect of submersion on leaves 337 



194 Cross-section of the ribbon-shaped leaves of Arrowhead 338 



195 Leaves of Water-buttercup (water-leaf and air-leaf) 339 



196 Lower epidermis of Water-polygonum 340 



197 Leaves of Dandelion, normal and in saturated atmosphere 342 



198 Gorse, normal and in saturated atmosphere 343 



199 Leaves of Prickly Lettuce (sun- and shade-leaves) 344 



200 Beech leaves (sun- and shade-leaves) 345 



201 The effect of wind on the growth of a tree trunk' 348 



202 Shows how branches are stunted and killed on the windward side 349 



203 The result of having branches mainly on one side (as in preceding 



figure ) 350 



204 Branch of Ivy Geranium 354 



205 Different kinds of bacteria 362 



206 Steam sterilizer 363 



207 Tumbler containing a slice of boiled potato 365 



208 A scraping from a potato culture 367 



209 Funnel with neck removed so as to fit into a tumbler 369 



210 Flat bottle containing gelatin (for "plate culture ") 370 



211 Chart showing the distribution of cholera cases in the Hamburg epi- 



demic of 1892 373 



212 Stab cultures in gelatin 375 



213 Yeast-cells budding 390 



214 Black Mould of bread 391 



215 Same beginning to show spores at the edges of the bread 392 



216 More advanced stage of spore formation 393 



217 Portion of the mycelium 394 



218 Black Mould of bread showing manner in which mycelium sends out 



root-like branches at short intervals 395 



219 A single spore case of the Black Mould of bread 395 



