238 DAVENPORT HOOKER 



ment, instead of flowing in a special cytoplasmic medium, occu- 

 pies a constant intracellular and interanastomosing canal system. 

 Within this closed system the pigment moves out into the proc- 

 esses or back into the cell body. Franz ('08 and '10), on the 

 other hand, would have the pigment granules in teleosts move 

 along constant rods in the cell and thus assume a radial position 

 to the nucleus. 



According to Keeble and Gamble ('05), the chromatophores 

 of Crangon are fixed stellate cells having their cytoplasm differ- 

 entiated "into a firmer, more refractive ectoplasmic wall and a 

 viscous endoplasm." During the process of expansion, "the 

 tubular branches become injected with protoplasm and pigment," 

 while in the contracted phase, "the tubes show up empty and 

 refractive, with here and there a nucleus pressed against their 

 walls."- Such a cell is represented in figure 6 of their plate 1 

 and shows the pigment-containing cytoplasm contracted into the 

 cell body, leaving an empty space in the processes. 



Biedermann ('92), and Ballowitz in his earlier papers ('93 a, 

 b and c), take a middle position. Both these authors claimed 

 that, while the chromatophores may, to some extent, shorten 

 their processes, the latter are never completely withdrawn. 



A large number of investigators hold that the chromatophores 

 are amoeboid. The majority of them, however, consider that 

 these cells expand and contract in the intercellular spaces, with- 

 out any definite path being prescribed for them. Ficalbi ('96) 

 and a few others, express the \'iew that there is no preformed 

 pathway, Init that the chromatophores may send out pseudopodia 

 in any direction. This same idea is probably held by many 

 others, such as von Wittich ('54), Busch ('56), Leydig ('57, '73), 

 Hering and Hoyer ('69), G. Pouchet ('76), Ehrmann ('92), Hal- 

 pern ('91), Fischel ('96) and Verworn ('09). 



A. Frohlich ('10) in a paper on Palaemon, was the first to 

 note that the chromatophores were amoeboid cells which occu- 

 pied fixed spaces in the tissues, within which they expanded 

 and contracted. He states, "die mikroskopische Untersuchung 



- Loc. cit., page 4. 



