lO BULLETIN OF THE BUREAU OF FISHERIES. 



CHANGES IN DISTRIBUTION OF PIGMENT IN CHROMATOPHORES. 



Changes in the distribution of the pigment granules in chromatophores have been 

 studied by many investigators in both invertebrate and vertebrate animals. Never- 

 theless, the manner in which these changes are brought about remains a controverted 

 question. Two theories prevail at present. According to the one, the chromatophores 

 contract and expand in an ameboid manner. Among the supporters of this theory 

 may be mentioned von Wittich (1854), Busch (1856), Leydig (1857, 1873), Hering and 

 Hoyer (1869), Pouchet (1876), Halpern (1891), Ehrmaim (1892), Ficabli (1896), Verworn 

 (1909), Froelich (1910), Holmes (1913), and Hooker (1912, 1914). According to the 

 other theory, changes in the distribution of the pigment do not involve essential changes 

 in the form of the chromatophore, but the pigment granules move through the protoplasm 

 or in fixed canals in it. Among the supporters of this theory may be mentioned Briicke 

 (1852), Harless (1854), Virchow (1854), Lister (1858), Solger (1889), Biedermann 

 (1892), Zimmermann (1893), Keeble and Gamble (1905), Kahn and Lieben (1907), 



Winkler (1910), Degner (191 2), Ballowitz 

 (1893, 1912, 1913, 1914), Franz (1908, 

 1910), and Spaeth (1913). 



That it is quite impossible in fresh 

 preparations of the skin or in living fishes 

 to observe the limits of the processes radi- 

 ating from the central area of a mature 

 chromatophore except in its fully expanded 



Fig. 4. — Camera lucida drawings taken at approximately lo- j*i' • j.i ■ e ^ 



minute intervals of a pigment eeU in an embroyo of Lucan.a Condition IS the COmmoU experience of UOt a 



parva 40 hours after fertilization. The stippled areas show few obsCrVCrS. That individual chrOmatO- 



the distribution of the pigment. i_ i j /i •j_ c 



phores possess a more or less definite form 

 and that this form is retained, i. e., the position of each radial process remains apparently 

 fixed, after repeated so-called "contractions" and "expansions" has been observed 

 by many investigators. Therefore, if the processes radiating from the central area 

 of a chromatophore are in turn retracted and extended, they must be composed of 

 relatively fluid protoplasm and occupy more or less definite tissue spaces. That such 

 is the case is maintained especially by Froelich (1910) and Hooker (19 14). 



In isolated cells of the larvae of Hyla remolla and Diemyctylus torosus containing 

 black pigment Hoknes (1913) observed unmistakable ameboid movements. While 

 he admits the possibility that in the adult the cell processes of the chromatophores 

 may be more fixed in outline, he still maintains that the extent to which ameboid 

 movements occur in the pigment cells of larvae ought to suggest skepticism as to the 

 commonly accepted view that the pigment moves within the cell. 



That ameboid movement occurs in the pigment cells of larval fishes is well known. 

 The accompanying figure (text fig. 4) shows a series of camera lucida drawings taken 

 at approximately lo-minute intervals of a cell containing yellow pigment in an embryo 

 of Lucania parva 40 hours after fertilization^ 



The unshaded areas in these drawings illustrate areas free from pigment. The 

 behavior of the pigment in the early pigment cells in embryos of this species is described 

 by the writer as follows: 



The pigment granules arise in the central region of the cell and gradually push out toward the 

 periphery. Until pigment is present in all parts of the cell the parts free from pigment remain clear. 



