[ 233 ] 



^be 3nfluence of Xigbt on ilfe. 



By W. Thomson. 



'S 



92i»- 



HE object of this paper is to gather together from 

 the world of nature a few examples of the influence 

 which light exerts upon life, so that by the con- 

 sideration of its effects in individual instances we 

 may the more easily be led to a more perfect 

 appreciation of its influence upon all living things. 

 -^/J^V^- That light plays an important part in the present 

 pjV\'^ economy is, of course, admitted at once by every- 

 one; but it requires, at least by some of us, a little 

 consideration before we can thoroughly grasp the full truth of 

 such a statement as that made by Prof. Frankland in the Nine- 

 teenth Century for May, 1894 : — "Almost every exhibition of force 

 with which we are acquainted on the earth is wholly due, either 

 directly or indirectly, to the influence of the sun through those 

 rays which reach us after traversing 93,000,000 miles of space. 

 Of the whole energy sent forth by the sun, we know that only an 

 excessively minute fraction — not more than one twenty-two hundred 

 millionth part (1/2,200,000,000) — is intercepted by the earth at all. 

 But in spite of the enormous distance traversed and the small 

 fraction of this radiant energy which we are only able to 'trap,' 

 modern science has shown us that we owe almost everything that 

 we have to its agency, and the remarkable manner in which it 

 controls the phenomena of our earth is daily receiving fresh illus- 

 tration and support." 



The commonest phenomena are very often those to which we 

 give the least attention. When an earthquake suddenly occurs, 

 men are forced to give heed to it; but as the sun continues from 

 day to day exerting its mighty influence, and silently keeping in 

 continual motion the wheels of life, there are few who regard it 

 with more than a common observation. Night follows day, week 

 succeeds week, the sun rises, the sun sets, and few are there who 

 consider for one moment what would take place if the sun set 

 and rose no more (that is, if continual night were to be the order 

 of things) ; or what would take place if the sun rose and set no 



International Journal of Microscopy and Natural Science. 



Third Series. Vol. V. r 



