440 Eimer on Gi'owtk and Inheritance 



cannot be said to be an inherited one in spite of the milHons 

 of generations of vegetable organisms which have all possessed 

 that tint ; because when young plants are reared in the dark 

 they remain colourless.^ 



* The profound action of light on the whole physical constitution of 

 the plant body, on the whole physiology of plants, is shown by the 

 fact that many tropical plants — as, for example, the South American 

 species of Bougainvillea, in European hothouses either do not bloom 

 at all, or only incompletely, in spite of all application of warmth, on 

 account of the deficiency of light.' 



Various kinds of tropical plants die in our botanic gardens 

 in the Regent's Park when we have a succession of such 

 days of overhead darkness as now and then occur in London. 

 No amount of warmth supplied to them will enable them to 

 escape the fatal consequences of such darkness. An instruc- 

 tive example is found amongst animals in the case of the 

 Proteus of the caverns of Carniola and Istria. This animal 

 is at first colourless, but if it be kept in the light it becomes 

 coloured.^ 



The effects of climate on cultivated plants have been well 

 shown by P. C. Schubeler with respect to those of Scandi- 

 navia. When various cereals in Norway and Sweden are 

 gradually transported from the plains to mountain districts, 

 they can be accustomed not only to develop in the same or 

 even in a shorter time than in their native region, but even 

 at a lower average temperature ! 



When such grain, after it has been grown for several years 

 in the mountain regions, is again sown in its native soil, it 

 ripens at first earher than other grain of the same kind which 

 has been cultivated uninterruptedly in the plains. 



With respect to a variety of phenomena of this kind 

 Professor Eimer observes : — ^ 



' It is a proposition of special importance to my argument, as well 

 1 P. 90. 2 p^ 144^ 3 pp, 95^ 96. 



