PHOTOPHORES OF DECAPOD CRUSTACEA 



335 



bers of the group, there is Uttle doubt that the structure under discussion is truly a 

 cell. Its limits are defined by a definite membrane within which is the nucleus. The cell 

 immediately to the left of the guide-line, phot.c. i in Fig. 14, shows a complete and 

 normal nucleus, but apart from a finely granular, lightly staining substance on the cell 

 wall remote from the nucleus no other contents are visible. This substance may be 

 cytoplasmic, but for reasons which will be given later this is unlikely. In the neigh- 

 bouring cell (Fig. I ^, phot.c. i) the nucleus shows signs of degeneration, being irregular 

 and with apparently an incomplete nuclear membrane. In the next most superficial 

 layer the cells (Fig. 14, phot.c. 2) have the appearance of being products of the con- 

 tinuation of the process. The nucleus is either absent, or is reduced to a deposit of 

 nuclear material at the proximal end of the cell, while at the opposite end lies a deposit 

 of the granular material seen in the cells of the previous layer. In the most superficial 



phot.nv. 

 photc.l. 



phof.c.2 



hof.c.3 



n.chit.ep. 



Fig. 14. Part of a longitudinal section through the right fifth thoracic Hmb of Hoplophonis novae-zealaiidiae, showing the 

 luminous organ at the proximal end of the carpus. Fixed Duboscq, Delafield's haematoxylin and eosin. A similar section 

 is seen in the photograph in Plate XXV, fig. 3. c.b. central body; chit, chitin; m. adjacent striated muscle; n.chit.ep. 

 nucleus of chitogenous epithelium; n.r.c. nucleus of reflector cell; phot.c. i, phot.c. 2, phot.c. 3, three successive phases in 

 the appearance of the photogenic cells; phot.nv. photophore nerve. 



