154 INFLUENCE OF LIGHT. 



consequently a development of animal and vegetable 

 forms may occur where the human eye can detect no 

 light ; and under such conditions the Proteus may be 

 produced in its cavernous abodes, and also those creatures 

 which live buried deep in mud. Some further con- 

 sideration of the probable agency of light will occupy us, 

 when we come to examine the phenomena of vital 

 forces. 



Light is essentially necessary to vegetable life ; and 

 to it science refers the powers which the plant possesses 

 of separating carbon from the air breathed by the 

 leaves, and .secreting it within its tissues for the pur- 

 pose of adding to its woody structure. As, however, 

 we have, in the growing plant, the action of several 

 physical powers exerted to different ends at the same 

 time, the remarkable facts which connect themselves 

 with vegetable chemistry and physiology are deferred for 

 a separate examination. 



The power of the solar rays to produce in bodies that 

 peculiar gleaming light which we call phosphorescence, 

 and the curious conditions under which this phenome- 

 non is sometimes apparent, independent of the sun's 

 direct influence, present a very remarkable chapter in 

 the science of luminous powers. 



The phosphorescence of animals is amongst the most 

 surprising of nature's phenomena, and it is not the 

 less so from our almost entire ignorance of the cause of 

 it. Many very poetical fancies have been applied in 

 description of these luminous creations ; and imagina- 

 tion has found reason why they should be gifted with 

 these extraordinary powers. The glow-worm lights her 

 lamp to lure her lover to her bower, and the luminous 

 animalcules of the ocean are employed in lighting up 

 the fathomless depths where the sun's rays cannot 

 penetrate, to aid its monsters in their search for prey. 

 " The lamp of love the pharos the telegraph of the 

 night, which scintillates and marks, in the silence of 



