Apr. ISytJ.] BOTANICAL SOCIFITY OF EDINBURGH. 535 



very insuflficiently known, and the ten years which liave 

 elapsed since Ivrukenberg's work have not advanced our 

 knowledge much. They are probably of fatty nature, 

 (lood examples of lipochromes are the colouring matters of 

 the feathers of the ibis or cardinal bird, and of the connnon 

 carrot. As compared with animal lipochromes, those of 

 plants appear to be characterised by a greater readiness to 

 crystallise. Thus Krukenberg never succeeded in crystall- 

 ising tetronerythrin, the animal lipochrome mentioned 

 above, with which he worked much ; and among the vast 

 number of animal lipochromes, that of the yolk of liens' 

 eggs seems to have been almost the only one crystallised. 

 Among plant lipochromes, on the other hand, that of the 

 carrot occurs naturally in crystals, while almost every 

 worker with chlorophyll has obtained one of the associated 

 lipochromes in a crystalline condition. This result is, 

 perhaps, due to the fact that the lipochromes of plants 

 occur in a purer condition than those of animals, but 

 comparative investigations are few. Another peculiarity 

 which may probably one day prove of service in the 

 classification of lipochromes, is the reaction with iodine in 

 potassium iodide. With this reagent some, but not all 

 the lipochromes, are coloured a bluish green, the reaction 

 being certainly much commoner with vegetable lipo- 

 chromes than with animal. Thus Mr. Cunningham and 

 Dr. MacMunn (3) who investigated the lipochromes of 

 twenty-two species of fishes, distributed in fifteen genera, 

 did not succeed in a single case in obtaining a definite 

 colouration with iodine, although in some cases they 

 obtained the reaction with Schultze's fluid. On the other 

 hand, in the case of the lipochromes of Fungi, a greenish 

 colour with iodine is usually readily obtained (see Zopf in 

 Schenk's Handbuch der Botanik, vol. iv.), and this is 

 generally true of plant lipochromes. It is possible that 

 this again is an indication that the lipochromes of plants 

 usually occur in a purer condition than those of animals. 



First, as to the distribution of the lipochromes of plants. 

 Lipochromes are associated with true chlorophyll in the 

 chlorophyll bodies of the green Algiv, the higher crypto- 

 gams, and phanerogams. Phycoxanthin, an apparently 

 well-defined lipochrome, occurs in the Phycochromaceae, 



