specific modifications of Japan Carahi. 509 



globe, must there not be some persistent, ever-continuing 

 action, which never in all the vicissitudes to which plants 

 are subject relaxes, or suspends, its active operation ? 

 And what is this but solar rays, the comparatively un- 

 changing action of the sun ? Throughout ages the sur- 

 face of the globe, with its climate and every physical 

 condition in it, has been changing, yet we believe the 

 foliage of the coal-measures was green. 



A simple evidence that greenness in vegetation is 

 owing to light is, that a plant hidden away in a dark 

 cellar grows rapidly and becomes blanched, that is, it 

 ceases when brought to the light to reflect from its leaves 

 green rays, but the relatively permanent character of its 

 organisation soon causes the normal colour to appear on 

 re-exposure to light-rays. Light, while it checks growth 

 in vegetation, has an effect on the material substance of 

 it, and causes it to absorb those rays which make it 

 appear green to us, but when removed from the light 

 it becomes white. Feeding on. vegetation, the older 

 organism, as compared to animal life, are green cater- 

 pillars, and the greenness of these larvae, by analogous 

 argument, may be set down as acquired under the 

 same natural processes, for the influences which have 

 acted on the vegetation have been sufficiently con- 

 tinuous on the larvae to cause them also to absorb 

 the same rays. There is no reason why a caterpillar 

 having a system which can admit light, after the 

 manner of a leaf, should not permanently become green 

 under the same conditions as a leaf, if an adequate 

 time be accorded to it, for light is a movement which is 

 of sufficient energy to act mechanically on such sub- 

 stances as those of which both consist. And from the 

 universal greenness in the vegetable kingdom we see 

 Nature has a general tendency to display this colour in 

 the flora of all countries ; and we see it also in other 

 organisms through which light can pass in a like man- 

 ner as through leaves ; and of these I shall speak later. 



At a watering-place this summer I saw the shingle of 

 the beach left in ridges by a receding tide, and these 

 ridges were, as any one could see by their continuity 

 along the shore, the result of the wave-movements of 

 the sea. "When it was rough the ridges were separated 

 by a wide dip, and in smooth weather the dips were 

 nearer together. They were the result of wave-move- 

 ment, and corresponded to the motion of the water. 



