Apr. 1896.] BOTANICAL SOCIETY' OF EDINBURGH. 549 



presence of anthocyau, or of other derivatives of the 

 tannins, in flowers and fruits is essentially the same 

 phenomenon as their appearance in young growing shoots, 

 and in injured tissues. Whatever part birds and insects 

 have played in the development of the colours of flowers 

 and fruits, it can only have been the acceleration of the 

 movement of organisms along lines of development upon 

 which their own inherent tendencies have led them. It is 

 most probable that the efiect of the choice of birds and 

 insects has been to convert a merely indifferent property 

 into one important for the maintenance of the species. 

 The colours of the rose and tulip were primarily of no more 

 importance to them than the indican of Indigofcra is to it 

 now, and all are still facts of the same nature. The result 

 of the preference of the bee has been to render the colour 

 of the rose of some importance to the species, but the colour 

 is independent of this preference, and is no more likely to 

 disappear, if the bee's preference were to disappear, 

 than is the hajmatoxylon of Ilannatoxylon campcchi- 

 anum likely to disappear if man's preference for it 

 faded. 



It may be said that the occurrence of white flowers is 

 contrary to this reasoning, because here there is no pigment 

 at all, and yet the aesthetic efiect is well-marked. On 

 the other hand, a very similar appearance of whiteness 

 occurs in many variegated leaves. See Hassack (7). 

 Here there is no doubt that the albinism is due to 

 degeneration, and is probably a consequence of the 

 artificial conditions of cultivation. It is again an 

 indication of diminishing capacity for assimilation, 

 and may therefore be naturally expected in floral 

 leaves. 



On the whole, a consideration of the pigments of plants 

 certainly seems to support the view, now rendered familiar 

 by Mr. Bateson's work, that conspicuous variations are 

 determinate rather than indefinite, are primarily dependent 

 upon the physical and chemical conditions existing within 

 the organism, rather than upon the result of the selective 

 action of other organisms working upon minute fortui- 

 tous variations, as "Weismann and his followers would 

 maintain. 



