AMOEBOID MOVEMENT IN THE CORIAL MELANO- 

 PHORES OF RANAi 



DAVENPORT HOOKER 



AndloDiical Ldhoriitory, Medical DeparlmeuL of Yale University 



THREE FIGURES 



In the last sixty years, the capability of certain animals to 

 change their coloration at frequent intervals has received con- 

 siderable attention iDoth from its physiological and morpho- 

 logical aspects. WTiile investigators generally are more or less 

 agreed in regard to various elements which cause such changes, 

 there is still much divergence of opinion concerning the manner 

 in which pigment migration is produced in or by the chromato- 

 phore. ]Many in\'estigators claim that the chromatophores are 

 actively mo\'ing amoeboid cells, while an even larger number 

 maintain that they are fixed. Between these two extremes, 

 many intermediate views have been expressed. Indeed, from a 

 review of the literature, it is evident that no less than seven 

 hypotheses have been advanced. 



The hypothesis which has had by far the greatest number of 

 supporters, assumes that the chromatophore is a fixed stellate 

 cell within which the pigment, carried in a rather fluid cytoplasm, 

 streams into and out of the processes of the cell during 'expan- 

 sion' and 'contraction.' This view was first proposed by Brlicke 

 ('52) and has since been reiterated by Harless ('54), Virchow 

 ('54), Lister ('58), Solger ('89), Zimmermann ('93 a), Kahn and 

 Lieben ('07), Winkler ('10), Degner ('12), Spaeth ('13) and others. 



Ballowitz ('13), working on teleosts, has proposed another 

 hypothesis which is, in a certain sense, a culmination to the 

 foregoing. According to him, the cells are fixed, but the pig- 



' The writer is indc'htecl to the Francis E. Looinis Research Fuiul of the Medical 

 Department of Vah> rniversity for apparatus and material used in this research. 



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