298 Mr Philip Sewell on the [sess. lii. 



production of the most individualised flowers, there we may 

 expect the colour to be more intense, but we cannot say that 

 the intensification is entirely the result of natural selection. 



But as giving us the first hint of a cause of colour-change, 

 we may refer again to the passage, written twenty-five years 

 ago, by ]\Ir Spencer in his Principles of Biology : — " Incipient 

 floral colour existed among the Cryptogams and among all 



young shoots of spring Failure of nutrition may be 



expected in parts the most remote from the roots, the ends of 

 lateral axes are therefore the most probable points of fructi- 

 fication But "if these points at which nutrition is 



failing are also the points at which the colours inherited from 

 lower types are likely to recur, then we may infer that the 

 organs of fructification will not unfrequently coexist with 

 such colours at the ends of such axes." 



Here it will be seen tliat Mr Spencer accounts for the co- 

 existence of colour and of flowers, but he fails to see the real 

 physiological significance of their correlation. He attributes 

 the appearance of colour at the ends of axes to lieredity, not 

 to lack of nutrition. We meet with various re-statements of 

 this assertion of Spencer's by other writers, as, for example, in 

 Colotir Sensr, where this passage occurs : — " We can hardly 

 resist the inference that coloured whorls represent an intensi- 

 ficatioii of the natural tint, such as is to be seen in spring 

 shoots and in autunni leaves." Elsewhere, Mr Grant Allen 

 notices more clearly than did Mr Spencer, as judged by the 

 above extract, that the physiological condition of such highly 

 coloured parts is that " they are expenders, not a(;cuinulators, 

 of energy." We may take this statement, or we may take the 

 statement by Vines, "thai ('(ildurin^- matters are physiologi- 

 cally waste ])r(jducts," as roughly in(hcating the position we 

 wish to emphasise, viz., that, in contrast to the grewi of cldoro- 

 phyll, "coloiii " is U) 1)0 regarded essentially as a product of 

 a destructive metabolism (kataljolism) in tlie cells in wliich 

 it occurs. 



Microscopic examination as to the actual conditions of 

 the colour-containing cells has revealed to us, in the hands 

 of Schimpcr, that not only docs the colouring matter result 

 as a product from th(! (h^stiuction of the; ])i'otop]iism of the 

 corpuscles, Ijut that " its develo])ment, in whiit are to become 

 chromoplasts, is fretpiently attended l)y a disappearance of 



