1867.] Light and Darkness. 345 



Its absence or presence causes marked modifications, not only 

 in the colours of plants, but in their growth. It attracts vege- 

 table forms or parts of them in the most extraordinary manner, 

 and with recurring regularity. A. wonderful sight, well known 

 to microscopists, is that of the little volvox-globator, gathered 

 in a green mass towards the light when some water containing 

 these exquisite forms is exposed to its influence. Every child has 

 watched the sunflower as its great round face is turned, as though 

 by some machinery within, and follows the orb of day in its course 

 through the heavens ; and does not the gastronomic epicure well 

 know that his asparagus, if carefully bedded up and kept in 

 darkness, will not have the green hue which it assumes as soon as 

 its head peeps above the soil ? 



And as to men and animals, we have only to look at the stunted 

 creatures of the dark and cold regions of the world; or at those 

 who are bred underground or in the dismal courts of large cities in 

 our own temperate zone, to be satisfied that with light we have robust, 

 strong, and well-developed bodies ; and without it, the reverse of these 

 qualities. 



As we have already stated, the undulatory theory of light is now 

 the accepted theory ; and although the nature of the interplanetary 

 ether which fills all space is a matter of individual conception, yet 

 the presence of some such medium must be recognized along with 

 the dynamic theory. And when we come to consider the nature of 

 those material forms and organizations which must be permeated 

 by that infinitely attenuated form of matter before light can 

 penetrate them, and compare some of the transparent solids with 

 fluids or gases which are only partially translucent, we become 

 still more puzzled to understand the character of the medium upon 

 which the force acts that we term light. The arrangement of the 

 atoms which exclude it from one portion of our precious organ of 

 sight, and concentrate it in another, are truly marvellous, and sad 

 indeed is the fate of the creature in whom the natural order of the 

 parts is so disturbed, that whilst all is bright, heavenly, smiling 

 light without, there is nought but gloom and darkness within. 



Dr. Winslow tells us but little worth remembering, and almost 

 nothing that is new, concerning the physiological effect of Light, 

 and sums up his information upon that portion of the subject with 

 which we should have supposed him to be the best acquainted 

 (namely, the influence of light upon the insane), with the admission 

 that he knows little or nothing about it, and in these words, " I freely 

 admit that placing but little faith in what has been recorded or said 

 on the subject, I have not kept any systematic register as to the 

 effect of different phases of the moon on the insane."* 



Of the modern theories of light we take him to be ignorant, for 



* P. 233. 

 VOL. IV. 2 A 



