n8 SCIENCE PROGRESS. 



bulia quadripunctata. The second type of chromatophore 

 was found in Tiedemannia clirysotincta, and consists of a 

 single stellate cell with much branched processes, swollen 

 at their ends. The cell consists of an outer non-contractile 

 membrane and a central hyaline fluid substance containing 

 pigment granules in suspension. The hyaline substance is 

 markedly contractile, and may concentrate itself with the 

 pigment entirely within the central body of the cell, or may 

 expand to the tips of the processes, leaving the central part 

 of the cell empty. The processes frequently contain pig- 

 ment in one half while the other half is empty. 



It is clear that the first of these two types of chromato- 

 phore is allied to that found in the Cephalopoda, while the 

 second closely resembles the chromatophore of Vertebrata, 

 as described by Brticke in the Chamadeon, Lister in the 

 Frog, and Ballowitz in the Fish. 



With regard to the chromatophores of Cephalopods a 

 mass of controversial literature has accumulated during the 

 last twenty years, and has almost taken the form of another 

 Franco-German war, owing to the way in which the prin- 

 cipal investigators have grouped themselves around the 

 central question. Harless's (12) early interpretation of 

 the chromatophore as consisting of a central passive pig- 

 ment-cell with radial contractile fibre-cells was confirmed 

 by H. Miiller, Boll (/. c), and other writers, and has been 

 generally accepted as correct. But Harting (13) in 1874 

 opposed this interpretation, denied the contractile power of 

 the radial fibres, and concluded that the power of altering 

 the form of the chromatophore must reside within the 

 protoplasm of the central cell itself. He regarded the 

 phase of contraction as the active phase of the chroma- 

 tophore. 



Harting's views have obtained no acceptance except in 

 France, where with slight modifications they have been 

 restated with considerable emphasis, though it cannot be 

 said with satisfactory evidence, by Blanchard (14), Girod 

 (15), and Joubin (16). 



On the other hand, the investigations of Kliemensiewicz 

 (17) have furnished a very convincing series of observations 



