PHOTOPHORES OF DECAPOD CRUSTACEA 



317 



Dorsal to the above cells, which may be referred to as lens cells, occurs a zone, seven 

 or eight cells in depth, possessing a pronouncedly different structure. The cells com- 

 posing it (Fig. 3 and Plate XXIV, fig. 4, vac.c.) are columnar, of almost uniform size, and 

 are regularly arranged. Each cell is highly vacuolated, its cytoplasm being distributed in 

 a uniform and well-defined layer around the sides and basal end of the cell, while at the 

 distal end (that nearest the lumen of the tubule) it forms a deeper zone, which is in turn 



lOOp 



refr. 



ere. 



vac c. 



ercLjt 



Fie ^ Oblique transverse section through one of the tubules of the antero-lateral portion of the liver of 

 sLstes corniadum, enlarged from the section seen m Fig. 2. er.c. erupting cell of tubule; er.cyt eioipted 

 cytoplasm lying within the lumen of the tubule; I.e. "lens" cell; ref.r. refractile rods; vac.c. vacuolated cell. 



vacuolated and presents a frothy appearance. This vacuolated distal tip is best developed 

 in the more ventral cells of this zone and progressively disappears in passing to the more 

 dorsal cells, which possess only a uniform distal mass of cytoplasm thicker than that 

 around the remainder of the periphery of the cell. As a result of this arrangement of 

 the cytoplasmic portion of the cell, the greater part of the cell body is occupied by a large 

 vacuole, within which float scattered masses of cytoplasm having apparently the same 



2-2 



