Apr. 1896.] BOTANICAL SOCIETY OF EDINBUKGH. 543 



some valley plants to a mountainous district, and found 

 that only those which became red flourished. 



Hassack (7), studying especially the case of coloured 

 leaves, also regards the colour as an adaptation, but adds 

 that it is also a direct result of the action of light. 

 Wigand with greater cautiou says that the favouring 

 conditions are feeble or suppressed assimilation and strong 

 light. Pick (lo), on experimental grounds of very doubt- 

 ful validity, holds that the pigment is of direct importance 

 in the transport of starch, and believes that the conditions 

 of formation are sunlight and low temperature — two 

 somewhat opposed factors. The anthocyans of flowers 

 and fruits are of course usually ascribed to the continued 

 selection of insects and birds. 



In attempting to reach a decision as to the meaning of 

 anthocyan, the most important point is first to obtain a 

 definite statement as to the effect produced by its presence 

 in the cell-sap of leaves. Although the question involves 

 considerable technical difficulty, there seems little doubt 

 that careful experiments prove that leaves, such as those 

 of the copper beech, which contain abundant anthocyan 

 assimilate more slowly than ordinary green leaves. See for 

 example Jumelle (8). It might, however, be said that 

 although such examples as the copper beech are dependent 

 upon man for their persistence, yet, under certain circum- 

 stances, the diminished assimilation of red leaves and 

 shoots may be temporarily compensated by the preservation 

 of the chlorophyll, and that in this way the reddening of 

 conifer leaves in autumn is an advantage. This explanation 

 hardly, however, applies to the reddening of growing shoots 

 in spring. We can hardly suppose that the light is then 

 strong enough to lead to tlie decomposition of the 

 chlorophyll, especially in view of the fact that the red 

 colour is frequently lost when such parts have made their 

 growth. Further, the parts of the plants which frequently 

 redden on exposure to strong light are not such as to make 

 us suppose that the preservation of their chlorophyll is of 

 great importance, being usually stems, petioles, veins of the 

 leaf, etc. As far as the effect of external conditions is 

 concerned, we must note that the apparent contradiction 

 between the two usually assigned causes for the production 



