248 ON THE GAS GLANDS OF SOME TELEOSTEAN FISHES. 



Corvina nigra (PI. VII. fig. 59). 

 Fig. 59 (X 1). Appearance of " red body " in ventral wall of bladder. 



Sarffws rondeletii (PI. VIII. fig. 60). 

 Fig. 60 (X 1). Appearance of " red bodj^ " in ventral wall of bladder. 



JBalisfes capriscus (PI. VIII. fig. Gl). 



Fig. 61 (X 1). Appearance of " red body "in ventral wall of bladder. The "red 

 body " is, in this case, situated posteriorly in the bladder, not 

 anteriorly. 



Zeusfaher (PL VIII. figs. 62-64; PI. IX. fig. 65). 



Fig. 62 (X 1). Appearance of " red bodies " in ventral wall of bladder. R.M., rete 

 niirabile ; G.E., gas gland ; M., anterior muscular band. 



63 (X 375). Transverse section across base of massive gas gland showing syn- 



cytial masses which probablj' represent the regenerating portion of 

 tiie gland. Cell-outlines only become visible in the more periplieral 

 regions. The syncytial nuclei divide by ordinary mitosis and are 

 of several sizes, giant nuclei being among them. 



64 (X 666). Amitotic division of nuclei in some small giant cells, intermediate- 



sized cells and small cells of the gas gland. The nucleolus seems 

 to be the first part of the nucleus to divide. 



65 (X 375). A binucleated giant cell surrounded bj^ the ordinarj"- small cells.. 



Comijare the magnification of this with the last figure. 



Gaclus morrJina (PI. VIII. fig. 66). 



Fig. 66 (X 27). Semi-diagrammatic transverse section across "red body." R.M., 

 tufts of rete mirabile; G.E., gas gland epithelium; M.C., cap of 

 connective tissue ; B.L., bladder cavit3^ 



Cepohi rnbescens (PI. VIII. fig. 67; PI. IX. fig. 68). 



Fig. 67 (X 1). Appearance of " red body " in ventral wall of bladder. 



68 (X 333). Glandular epitlielium in transverse section. The perivascular 

 darkening of the cytoplasm is here very marked. The ducts of 

 the gland are very thin and inconspicuous. 



Fercafluviafilis (PI. IX. figs. 69-72). 



Fig. 69 (X 1). Appearance of branched "red bod3' " in ventral wall of bladder, the 

 portions of gas gland forming margins to the small fan-shaped 

 retia mirabilia. 



70 (X 1000). A small portion of the gas gland of Perca (fixed with Zenker)- 



showing the evolution of bubble-masses from the cytoplasm in 

 certain cells of the epithelium, consequent upon the experiment of 

 weighting the fish (Appendix B, cf. text-fig. 61, p. 240). 



71 (X 1000). Cells of the gas gland of Per ra (fixed with the Glacial-Absolute 



mixture) exhausted by the activity of the gland {cf. text-fig. 62). 

 One of tlie bladder-like structures is shown in connection ^^'ithone 

 of the cells. 



72 (X 1000). Unexhausted, i. e. inactive cells of the gas gland of Perca (fixed 



by the same method) for comparison with those of fig. 71. 



Nerophis ceqiiorius (PL IX. fig. 73). 



Fig. 73 (X 666). Five gas gland cells of Neropliii in contact with a capillary. This 

 figure, coloured to resemble my preparations as far as possible, 

 shows in the gas gland cell the "striped zone of cytoplasm next the 

 capillary wall (indicative of absorption) and the erythrocyte- 

 disintegration granular material present in the blood. 



