Fig. 4 



FIG. 3. Sub-mental photogenic gland of Monocenlris japonicus in horizontal 

 section at the level of its opening. X 16. chr, pigment layer; dt, emissory ducts; 

 rs, reservoir; se, secretion; se t, secretory tubules. 



FIG. 4. A portion of gland proper. X 640. cap, capillaries; col, collecting 

 tubule; con, connective tissue; se ep, secretory epithelium; se t, secretory tubule. 



FIG. 5. Basal part of a secretory tubule. X 1,250. con, connective tissue; 

 w, nuclei in epithelium; n', nuclei in secretion; se, secretion; se. ep, secretory 

 epithelium. 



FIG. 6. Sub-mental photogenic gland of Monocentris japonicus viewed by 

 transmitted light. X 16. 



FIG. 7. The same gland seen by reflected light. Crystalline deposit is rep- 

 resented in white. 



