PHOTOPHORES OF DECAPOD CRUSTACEA 



319 



perhaps they too may undergo eruption in a similar manner. This would lead to the 

 belief that there is no hard and fast distinction to be drawn between the cells of these 

 two zones. 



The rod-like bodies (Figs. 3, 4, ref.r.) which alone distinguish the dorsal cells of the 

 luminous portions of the tubules are slightly refractile spindle-shaped bodies, staining 

 deeply in acid fuchsin and arranged perpendicularly at the basal ends of the cells. They 

 do not extend completely to the basal end of the cell, for their tips end some little 

 distance from it, leaving a narrow but clear basal zone of cytoplasm. In haematoxylin- 

 stained preparations the rods are not visible. 



25l 





n.n.erc. 



degn 



Fig. 4. The dorsal portion of one of the luminous liver tubules of Sergestes comiculiim. Fixed Duboscq, 

 Delafield's haematoxylin and eosin. deg.u. degenerate nucleus lying in the lumen of the tubule; deg.n.er.c. 

 degenerating nucleus of an erupting cell; deg.n.ref.c. degenerating nucleus of a reflecting cell; n.n.er.c. 

 normal nucleus of an erupting cell ; n.n.ref.c. normal nucleus of a reflecting cell ; ref.r. refractile rod. 



The cells intervening between the dense luminous tubules and the digestive tubules 

 themselves are not remarkable. It should be stated that the normal liver tubules of 

 Sergestes are composed of highly vacuolated irregularly shaped cells whose nuclei are 

 almost completely achromatic. They thus have a very delicate and tenuous appearance, 

 and the organs of Pesta by contrast are very conspicuous. The intervening cells under 

 discussion are denser than those forming the digestive tubules, and their nuclei are rich 

 in chromatin. 



The cellular differentiation of the luminous tubules bears a considerable, if not 

 complete, relation to the coloration of the organs of Pesta as seen in fresh material 

 (pp. 314,315). The lower portion of the organ is described as Antwerp blue (Burkenroad) 

 or purplish black (Kemp), and would appear to be composed of those ventral parts of the 



