58 EXPERIMENTAL EVOLUTION LECT. 



A third fact, which must be noticed here, is the posi- 

 tive influence of the colour of environment on that of 

 animals. Mr. E. B. Poulton has recently studied this 

 matter, showing, in his important memoir published 

 in 1887, that many lepidopterous larvae are strongly 

 affected by the surrounding colour. The plates 

 which accompany his memoir illustrate the fact 

 very precisely. 



If we consider those freaks of colour which are 

 familiar to horticulturists under the name of variega- 

 tions, some interesting facts may be noticed. It has 

 been often questioned whether variegations are not 

 pathological symptoms, and whether variegated plants 

 are not more or less diseased. M. E. A. Carriere * has 

 carefully considered the matter, and his considerable 

 horticultural experience does not make him feel in- 

 clined to consider variegated plants as being diseased 

 at all. It even seems that in many cases, variegated 

 forms are healthier and stronger than the non- 

 variegated : for instance, the variegated Euouymus of 

 the Duke of Anjou variety. There is however one 

 fact which has been noticed concerning variegations 

 it is the impossibility of maintaining such plants with 

 their variegation in some localities. Many horticul- 

 turists have recorded the fact ; and while some com- 



1 Lcs Panachures sont dies des Maladies? Revue Horticole, 1884, 

 p. 198. 



