248 DAVENPORT HOOKER 



of which they fill in complete expansion, their expansion patterns 

 must always be identical for each given cell. These patterns 

 are forced upon the cell by the cavities in which they move. 



In an earlier paper (Hooker '12), the spaces occupied by the 

 melanophores in the frog were termed 'lymph spaces.' This 

 designation was used on account of the close resemblance of 

 these cavities to those in which the corneal cells lie, as described 

 by von Recklinghausen ('62). As a matter of fact, no proof 

 that these spaces contain lymph has been obtained, nor is it of 

 importance in this connection to prove it. However, it seems 

 probable that the spaces contain some fluid, though not in any 

 great quantity. 



Ficalbi ('96) believed the chromatophores to be fully amoe- 

 boid and to possess the capability of sending out pseudopodia 

 in any direction. The melanophores of frog larvae are just such 

 cells. Their cavities do not limit their motion and all their 

 changes of form are produced by protoplasmic pseudopodia. In 

 the corresponding cells of adult frogs, on the other hand, this 

 capability is hampered by the pecuharities of the containing 

 space. Within the central 'reservoir,' however, the pseudopodia 

 have free play. As any cell which changes its form by means 

 of pseudopodia is amoeboid, the melanophores of the frog are 

 of this type. 



Melanophores which have developed in plasma are amoeboid 

 and, not being limited by any space, move about in the medium. 

 This has been previously observed by Harrison ('10). Owing 

 to the fact that many types of cells become amoeboid in plasma 

 cultures, the value of this evidence in the present problem is 

 somewhat doubtful. There is, however, abundant proof of the 

 amoeboid nature of the melanophores from other sources. 



RESULTS 



1. The pigment granules contained within the melanophores 

 of larval and adult frogs are carried in the cell cytoplasm and 

 not in intracellular canals, along rod-like structures nor in a 

 specialized type of protoplasm. Further they show no definite 

 relation or arrangement to one another nor to the nucleus. 



