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ABSTRACTS OF MEMOIRS 



RECORDING WORK DONE AT THE PLY^NIOUTH LABORATORY. 



The Relation between Light and Pigment-formation in Creni'labrus 

 and Hippolyte. By Prof. F. W. Gamble, F.R.S. {Quart. Jour. 

 Micros. Science, Vol. LV, Pt. o, 1910.) 



The work on which this paper is based v.-as carried out at Plymouth in 

 1908 and 1909. The two species on which the main results were 

 investigated were Crenilahrus m el ops and Hiirpohjte variaus. liack- 

 grounds of weed and of painted glass were employed in order to test 

 the influence of reflected light. Light-filters transmitting red and 

 green respectively were used to determine the result of subjecting 

 1112)2)011/1 c to diffused monochromatic'light. 

 The following are the chief results : — 



(1) Crenilahrus. The effect of light reflected from backgrounds of 

 weeds and diluted with white light is different from the effect of light 

 transmitted through the same weeds and not largely diluted with white 

 light. In the former case the young animals generally assumed the 

 tint of their surroundings ; in the latter the dominant colouring was 

 that complementary to the brightest part of the transmitted spectrum. 



(2) llip2wli/te. Any female of this variably coloured prawn throws 

 larvai which are constant in coloration w^th the exception of the 

 broods of certain green parents. In other cases the colour (red) of the 

 Zoeae varies in intensity at the time of hatching with the amount of 

 red pigment in the female. 



Green females throw one of three kinds of larvie : (1) all red; (2) 

 colourless; or (3) a mixture of red and colourless in the proportion 

 of 3 to 1. 



The red larval pigment develops in the absence of light. The origin 

 of the yellow pigment has not been timed, but post-larval specimens 

 (4-5 mm. long) if kept in darkness develop into brown specimens. 



In pure green light similar (nearly colourless) specimens develop 

 into crimson specimens. The red and yellow pigments disappear. 



In pure red light the yellow pigment develops, and this together 

 with a variable amount of diffuse blue colouring give a green tint, or 

 a yellowish one. The colour of the food has apparently some influence 

 upon the result. 



