70 



The Colour-physiology of Higher Crustacea. [July 16, 



The cliromatophores are centres of metabolic activity, and from them 

 a nocturnal translocation of a blue substance takes place. There is 

 evidence that this blue substance is produced from, and at the expense 

 of, the diurnal chromatoph ore-pigments. The blue substance passes 

 from the chromatophore-<?entres, persists for a time in the body, and 

 ultimately disappears. 



C. Morphology. 



7. The chromatophore-system of Mysidean Schizopods is built upon 

 a, common plan, of which the various genera and species present 

 severally a constant modification. This system we call the primar}^ 

 chromatophore-system. To it the colour-pattern is due. 



8. Decapod Crustacea possesses a primary and a secondary system 

 of cliromatophores. The primary system appears in the embryo, is 

 completed in the " ilfys^-stage," and persists throughout life, but takes 

 no part in colour-pattern. 



The secondary system arises in an early stage of development, 

 increases in extent throughout life, and produces the colour-patterns of 

 the adolescent and adult. 



9. The chromatophores of the primary system are profusely 

 branched, few in numbers, segment-ally arranged and centralised ; 

 those of the secondary system are sparsely branched, numerous, 

 irregularly arranged and decentralised. 



D. Histology. 



10. The chromatophores of Mysidae are multicellular organs. 

 Those of the neural group are developed from the epidermis. Losing 

 their connection with the epidermis they acquire a close relation with 

 the central nervous system. The distribution of the primary 

 chromatophore-system follows that of the ganglionic parts of the 

 nervous system. 



11. The chromatophores of Decapods are plurinuclear connected 

 structures : their distribution is not confined to the ganglionic parts 

 of the nervous system. 



E. Taxonomy. 



12. The primary systems afford assistance in the determination of 

 genera and species. By their aid, animals in early, as well as in late, 

 stages of development may be diagnosed. 



F. Inheritance. 



13. The several adult colour-patterns of PaJeemon and Crawjon are 

 constant, and develop directly. The evidence tends to prove that 

 both secondary and primary chromatophore-systems are inherited. 



