PLATE XXIV 



Fig. I. Longitudinal section through one of the maxillary exopod photo- 

 phores of Sergestes regalis. Ventral surface downwards. Compare 

 with Fig. I. Fixed Duboscq, Mallory's triple stain, x 140. fib. 

 interwoven fibrils; nfib.m.c. nucleus of fibril mother cell; 

 phot.cen. photogenic centre. 



Fig. 2. Part of a transverse section through the cephalo-thorax of 

 Sergestes corniculiim, showing the right antero-lateral group of 

 luminous liver tubules (organ of Pesta) very heavily stained with 

 acid-fuchsin. Compare with Fig. 2. Fixed Duboscq, Mallory's 

 triple stain, xiio. 6r.cA. branchial chamber; /.<. luminous tubule; 

 n.l. normal liver. 



Fig. 3. The "mandibular organ" (luminous liver tubules) and part of 

 the mandible of Parapandalus richardi in transverse section. Com- 

 pare with Fig. 7. Fixed Duboscq. Delafield's haematoxylin and 

 eosin. xiio. /./. luminous tubule; ?nr/. mandible. 



Fig. 4. Some of the luminous tubules of the organ of Pesta enlarged 

 from the section seen in Plate XXIV, fig. 2. Compare with Fig. 3. 

 X 240. er.c. erupting cell of tubule ; er.cyt. erupted cytoplasm lying 

 within the lumen of the tubule ; I.e. lens cell ; vac.c. vacuolated cell. 



Fig. 5. The luminous portion of the mandibular organ of Parapandalus 

 richardi, enlarged from the section seen in Plate XXIV, fig. 3 and 

 Figs. 7 and 8. x 240. l.c.n.v. non-vacuolated liver cell ; l.t. luminous 

 tubule ; phot.c. photogenic cell. 



