THE EELATION BETWEEN LIGHT AND PIGMENT-FORMATION. 563 



mother, and it would be of great interest to know how they 

 were formed. 



In order to test the influence of food-pigments on the 

 development of pigment in Hippolyte, the following experi- 

 ment was carried out at Millport, N.B. A series of double 

 glass vessels were prepared, the Hippolyte being placed in 

 the inner chamber and a mass. of weed in the outer one. Two 

 series of pressure-bottles, one in diffused light, the other in 

 darkness, were set up for isolated specimens. The food 

 employed was chosen from the following: The natural alga 

 chopped up into fine pieces so as not to act as a massive back- 

 ground ; etiolated Laminaria, also subdivided ; the muscle of 

 Hyas, the colourless ovary of Hyas, and the scarlet, mature 

 ovary of the same crab. The specimens of Hippolyte em- 

 ployed were 5-7 mm. in length, colourless, and tending on 

 a black background to assume a faint brown-lined colour 

 pattern. 



Table A. — Feeding Experiment. 



Colour of Hippolyte after exposure to contrasted colours in 

 food and surroundings, Millport, 1909. Colourless foods 

 employed are crabs' muscle, etiolated Laminaria, and 

 colourless ovary of Hyas. The Hippolyte used were 

 from 6-8 mm. long and colourless to the naked eye. 

 Experiment lasted seven to ten days. 



