CONTENTS XI 



PAGE 



SECTION v.— PIGMENTS 225 



Chlorophyll 225 



Constitution ........••■ 231 



Action of alkalies 232 



Action of acid 233 



Crystalline and amorphous chlorophyll 233 



Relationship between chlorophyll and haemoglobin . . . 236 



Extraction of chlorophyll ........ 238^^. 



Carotinoids or yellow pigments accompanying chlorophyll . . . 241 



Carotin- 242 



Xanthophyll 243 



Fucoxanthin 243 



Anthoxanthins ........... 244 



Flavones and Xanthones ......... 244 



Yellow colouring matters derived from flavone .... 245 



Yellow colouring matters derived from xanthone .... 246 



Properties of anthoxanthins ........ 247 



Anthocyanins, Phycoerythrin, and Phycophaein ..... 248 



Connection between anthocyanins and anthoxanthins . . . -251 



Extraction of anthocyanins ......... 251 



Anthocyanins 252 



Properties .... ....... 254 



Reactions 256 



Physiological significance ........ 256 



Phycoerythrin 258 



Preparation 259 



Reactions 259 



Phycophaein 260 



SECTION VI.— NITROGEN BASES 263 



Alkaloids 265 



Classification 256 



Properties 269 



Reactions 270 



Isolation 271 



Origin of alkaloids in the plant 272 



Ptomaines ............ 274 



Purine bases ........... 276 



Physiological significance of nitrogen bases 280 



SECTION VII.— COLLOIDS 283 



Properties ............ 284 



Diffusibility 284 



Optical properties 285 



Change of state or gel formation 287 



Protective power .... ...... 291 



Classification of Colloids ......... 291 



Properties of suspensoids . . ...... 292 



Properties of emulsoids 293 



The nature of gels 294 



Adsorption ........... 295 



Enzyme action ol colloids ........ 297 



