vm] THE SIGNIFICANCE OF ANTHOCYANINS 135 



warmeabsorbierenden Blattrot besitzt die Pflanze ein Mittel, die Stoff- 

 und Kraftwechselprocesse zu beschleunigen." Stahl suggests that at such 

 low night temperature, Linum is unable to translocate starch and thus 

 the plant becomes 'starch-sick/ and synthetic reactions cannot proceed ; 

 but he admits that the experiments require further attention. He has 

 himself made observations upon cultures of Linum and Satureja at 

 Pontresina and found, after a night with temperature about C., in 

 the morning the Linum leaves were still full of starch, whereas Satureja 

 leaves were starch-free, although exposed during the previous day to 

 intense sunlight. Stahl's view on this function of anthocyanin was 

 also applied to autumnal leaves. 



Again, the reddening of stigmas of anemophilous flowers is considered 

 by Stahl to be another illustration of the value of the heating properties. 

 As examples of trees and plants possessing such a characteristic, he 

 quotes species of Populus, Salix, Platanus, Ulmus, Ostrya, Carpinus, 

 Corylus, Alnus, Acer, Fraxinus, Poterium sanguisorba and Rumex 

 scutatus, and of these, the trees, he points out, flower early in the year. 

 Hence the presence of anthocyanin is a special adaptation for raising 

 the temperature and thereby furthering the growth of the pollen-tube. 



Stahl next deals with his own suggestion as to a special significance 

 of anthocyanin which it possesses by virtue of its temperature-raising 

 properties. He maintains that anthocyanin is frequently found in 

 leaves of water-plants inhabiting marshy places ; also to a considerable 

 extent in the leaves of shade-loving plants in damp tropical regions. 

 The presence of anthocyanin in these leaves leads to a rise of tempera- 

 ture, and thereby accelerates transpiration which is rendered difficult 

 by the conditions of such habitats. He quotes as examples the red 

 under surfaces of leaves of Nymphaea, Villarsia and the frond of 

 Lemna ; of marsh plants, Orchis maculata, 0. latifolia, Ranunculus acris ; 

 of shady wood plants, Arum maculatum, Phyteuma spicatum, Hypochaeris 

 maculata. These are, however, insignificant as compared with tropical 

 plants of which he quotes many examples from Borneo, Java and Mexico, 

 of the orders Begoniaceae, Orchidaceae, Acanthaceae, Gesneriaceae, 

 Marantaceae, Araceae and Melastomaceae ; Stahl even goes so far as to 

 say that in the case of leaves which develop blotches of anthocyanin, 

 the lower leaves near the moist ground are more strongly marked than 

 the upper leaves which may not be marked at all (PolygonumPersicaria}. 

 Also in Java he has noted that shaded pitchers of Nepenthes lying on 

 the ground amongst ferns and mosses were deep red, while those borne 

 high up above the vegetation had only a slight reddening. 



