RED PIGMENT OF FLOWERING PLANTS. 413 



virtue of its absorbent qualities, of pushing forward trans- 

 location during the closing hours of the clay : in enabling 

 the plant to get a greater part of its work done while it 

 is day. 



The most important of Pick's expenments consisted in 

 the study of the starch of assimilation formed by Ricinus 

 leaves, and parts of leaves, whilst living behind various 

 screens. He placed, for four hours of the day, the lobes of a 

 leaf of a Ricimi-s plant behind, respectively, i, ruby glass, 2, 

 orange-coloured glass, 3, watery solution of the sap of 

 red beet-root; whilst the fourth was directly insolated during 

 the time of the experiment. He obtained, omitting those 

 in the case of the lobe behind the orange glass, the following 

 results : The lobe directly insolated contained much starch 

 in its spongy parenchyma but more in the palisade cells ; 

 that behind the red-sap solution contained much starch in 

 the conducting spongy tissue and less in the palisade ; 

 whilst in that behind ruby glass the starch was almost 

 entirely confined to the spongy parenchyma, only a trace 

 being found in the palisade tissue. 



Pick's interpretation of his experiments is, that the lobes 

 behind the red screens had assimilated as well and trans- 

 located better than those exposed to white light ; and there- 

 fore this augmented transport of carbohydrate is due to the 

 light absorbed by the anthocyan. 



Wortmann (28) criticises these conclusions very severely, 

 bringing forward the following objections : i, before these 

 inferences can legitimately be drawn it should be ascer- 

 tained whether the rays absorbed by the anthocyan can, 

 outside the living cell, increase the activity of diastase, the 

 agent of translocation. Positive evidence at present avail- 

 able shows that this is not so, Detmer having proved that 

 light is without influence on fermentation ; 2, the results of 

 Pick's experiments may be explained in quite another way. 

 Wortmann adopts Stahl's suggestion that the palisade 

 parenchyma of a leaf is an adaptation to bright light, the 

 spongy tissue to light of feeble intensity, and thus explains 

 Pick's results : that in bright light the palisade parenchyma 

 will assimilate most actively and starch will appear in its cells ; 



