610 F. W. GAMBLE AND F. W. KEEBLE. 



centres or bodies of the " chromatophores." The network is 

 continuous from one end of the body to the other^ and from 

 the right side to the left. By the aid of the microscope the 

 green patches can be resolved into yellow and blue pigments 

 lying in the same ^ processes : in other parts of the reticu- 

 lum yellow pigment may be seen close to the red. The 

 brown colour^ in factj is due to the superficial processes of 

 " chromatophores/' the bodies of which lie in the subjacent 

 connective tissue and give off other deep intermuscular pro- 

 cesses, which are only revealed after the removal of pieces of 

 the integument. The red pigment is fully expanded, the 

 yellow considerably less, and the blue very slightly. 



This blue pigment, which we here encounter for the first 

 time, is treated at some length in the section on Nocturnal 

 Coloration (Section V, p. 622), and we need say little about it 

 here, as it plays a much less important part as a rule in deter- 

 mining the tint of the prawn during the day than the red or 

 yellow. Whether, like these, it pre-exists stored up in the 

 centre of the "chromatophores," or can be, under suitable con- 

 ditions, rapidly manufactured out of the red or yellow pigment, 

 or whether both these alternatives contain something of the 

 truth, we have nob determined. Till our knowledge of the 

 chemical nature of the pigments — presumably lipochromes — 

 is extended in the way which Maly (1881) and Newbigin 

 (1897) have indicated, these questions must be left open. 



To return to our description of the pigment bodies in the 

 brown varieties of Hippolyte. In addition to the '^ chro- 

 matophores^' just described, blue spots in the sides of the 

 body, often visible to the naked eye, are of frequent but not 

 of constant occurrence (PL 35, fig. 21). 



These blue spots occur in other colour forms of Hippolyte 

 — for example, in green and variegated brown specimens, — 

 and the same description will apply to most cases. In form 

 and in size they are most variable. They may be spherical, 

 almost black by transmitted light, and provided with a few 

 short lighter coloured processes, or they may be elongated, 

 ' Or in closely apposed ones. 



