Literary Notices. 437 



ency, so that the larva is more like Afacro/iiysis than it is like the adult 

 form. This primary system persists unchanged in the adult but is 

 overlaid by a secondary, and sometimes even by a tertiary, system of 

 chromatophores. The pigments of this secondary system are either 

 absorbing or reflecting; the former, red, yellow, brown, violet and 

 diffuse blue, are the same in transmitted and reflected light, the latter 

 are only effective in reflected light, and appear white, yellow, greenish 

 or blue, as the case may be. 



The question is raised whether these chromatophore systems and 

 the color patterns resulting from them are inherited or acquired. After 

 marshalling the evidence the authors conclude that the primary sys- 

 tem, owing to its appearance in the earliest larval stages, and its per- 

 sistence in the adult, is inherited in all cases. In Crangoii and Palac- 

 711011 there is a steady, constant development of the secondary pattern 

 from the embryo to the adult, and hence the secondary system is 

 thought to be inherited iu these forms. In Hippolytc, however, there 

 does not seem to be any such constancy of development, but the dom- 

 inant coloi' pattern is rather a result of the action of the environment. 



Regarding the mechanism of pigment migration the authors hesi- 

 tate to express themselves. They are not inclined, however, to accept 

 Pocket's view that it is due to the active amoeboid movement of cell 

 processes, but prefer to account for it by the turgidity of the constitu- 

 ent cells of the centers, caused chiefly by the action of light, and con- 

 trolled to a greater or less extent by the nervous system. This view is 

 strengthened by the fact that in old Mysids "the pigment at times 

 bursts the frondose extremities of the chromatophores and exudes into 

 the surrounding tissues." Moreover, the origin of the chromatophores is 

 to be found, not in connective, but in glandular tissue, and their action 

 seems to be like that of a gland, continually secreting or transforming 

 pigment substances. 



In Hippolyte variaiis there is a regular alternation of the diurnal 

 color-pattern, due to red and yellow pigments, with the nocturnal, 

 which is blue. Under appropriate light stimulation the red and yel- 

 low pigments flow out through the branches, and when the stimulation 

 is withdrawn, these pigments contract and there is a diffusion of blue. 

 The authors think, however, that the blue pigment does not serve any 

 protective purpose, but is rather a by-product obtained by the trans- 

 formation of the yellow and red pigments, and "exudes from the 

 chromatophores, permeates the tissues and subsequently disappears." 



Perhaps the most interesting portion of the paper is the last sec- 

 tion, which deals with the influence of liarht on littoral Crustacea. 



