REPORT OF COMMISSIONERS OF INLAND FISHERIES. 251 



II. The Influence of Light on the Rate of Development. 



Insomuch as the writer has treated this subject in more detail in 

 another paper* the present consideration will be brief. The question 

 of the influence of light upon the rate of growth is, however, one of 

 no little importance to the general problems of the artificial propa- 

 gation of marine animals, and the writer hopes to be able at a later 

 date to present the result of further investigations which shall better 

 warrant the drawing of more far-reaching conclusions. 



In the preliminary consideration of this problem, the first question 

 which we may ask is, what influence do light and darkness appear 

 to have upon the development of animal life in general; and, con- 

 sequently, what effect might we expect it to have upon the young 

 lobster? In answer to this query it may be said that, so far as in- 

 vestigations to the present are concerned, the following facts, which 

 hold true both for vertebrates and for the lower forms of animals 

 (many of them marine), are generally admitted. 



1. That development of animal life in general is more rapid in 

 daylight (white light) than in absolute darkness. 



2. That development in twilight is more rapid than in either (a) 

 darkness or (b) daylight. 



3. That development under the influence of certain monochromatic 

 lights (blue or violet) is more rapid than in daylight, but, in most cases, 

 less rapid than under the influence of twilight. 



4. That the influence of white light may hasten destructive meta- 

 bolism in many forms, but that the evil influence of the red rays con- 

 tained in the white is not as detrimental to growth as the effect created 

 by totally excluding the blue and violet rays which are also contained 

 in the white, and from which, in many forms, the growth process derives 

 a certain stimulation. 



The hypothetical conclusion to which, in view of the general facts, 



♦"Regarding the rate of growth of the American lobster," Report of the Rhode Island 

 Commission of Inland Fisheries for 1905. Reprint 1906. 



