REPORT OF COMMISSIONERS OF INLAND FISHERIES. 57 



mental conditions have been found to possess a vast influence.* 

 It is not, however, within the intended scope of this paper to put 

 forth the results of extended experimentation, but to give briefly a 

 survey of some of the more common facts of color variation and 

 pigment development in decapod Crustacea, together with a pre- 

 liminary report of a series of observations extending over eleven 

 stages of Homarus Americanus — a series which includes the succes- 

 sive changes in color and coloration from the time of hatching to the 

 attainment of the adult color type. 



In the early stages of the lobster are found frequent and very 

 wide range of color variation. This may occur as successive color 

 changes from stage to stage, as variation in the color of different 

 individuals in the same stage, or again, in the changes in color through 

 which a single lobster may pass during a single stage. In the first 

 larval stages these variations occur as rapid and transitory, and yet 

 uniform, changes from one color to another. In the young adult 

 forms, however, although a wide difference in individual color is 

 manifest, the color and color pattern appears more permanent and 

 more constant to a given type when this type has been once estab- 

 lished, while the sudden, transitory changes so characteristic of the 

 larval stages are entirely absent. 



NATURE OF THE PIGMENTS AND OF THE CHROMATOPHORE SYSTEMS. 



The pigmentation of the lobster may be resolved into three dif- 

 ferent constituents, the blue, the red, and the yellow. The blue is a 

 soluble pigment, probably a lipochrome, dissolved in the blood, 

 while the red and the yellow pigments, which may be also lipo- 

 chromes, exist as a granular substance in certain cells, the chro- 

 matophores. Each one of these chromatophores is a granular 

 cytoplasmic body of neuroglia or stellate shape, having a center 



* Young flounders having been kept for sometime in tanks in the bottom of which mirrors 

 were placed, showed in many cases large pigmentation of the under side, which is usually white ; 

 which seemed to show that some external cause, as light, was responsible for the change. 



