46 PRODUCTION OF CHLOROPHYLL. [CH. II 



water, the parts which have been heated reveal, almost 

 at once, the chlorophyll. To obtain a solution of the red 

 colour the leaves must be killed by ether vapour, cut up 

 and placed in distilled water. Even in cold water the red 

 of Ricinus is soon decomposed. 



(63) Floridem. 



In some species at any rate, the colouring matter 

 reddens cold fresh water in which the sea-weeds are placed, 

 but the colour is destroyed by boiling. In Polysiphonia it 

 is not destroyed. 



(64) Brown sea-weeds. 



A portion of Fucus or Laminaria yields a brown colour 

 to water in which it is boiled — while the boiled thallus 

 shows a greenish colour and yields a green alcoholic 

 extract. But it is impossible as far as we have seen to 

 extract the whole of the colouring matters. 



Section D. Conditions necessary for production 

 of chlorophyll. Stiolation. Sun and shade leaves, 



(65) Formation of chlorophyll. 



Seedlings of any sort, e.g. cereals or cress (Lepi- 



dium) or mustard, or V. faba, are grown in the dark and 



are then placed in the morning in a good light close 



to the window and the time necessary for the production 



of a distinct green colour is noted^. 



1 Etiolation proper can only be observed in parts of plants which 

 have developed in the dark. The already formed chlorophyll may 

 become discoloured by starvation, but this is not etiolation. Many 

 leaves retain their green colour for a long time in darkness. 



