104 DR. W. X, F. WOODLAXD OX THE 



later, are closely associated with the larger veins. Lying along- 

 side the rete mirabile is the anterior extremity of the elongated 

 closed bladder (fig. 14), the wall of the anterior region of which 

 is very glandular and vascular. A little way behind the anterior 

 exti-emity of the bladder, the side of the rete next the bladder 

 comes into connection with the bladder epithelium (fig. 15), the 

 capillaries uniting (i. e. the arterial capillaries are uniting and 

 the venous capillaries are really here subdividing to form the 

 minute venous capillaries of the rete) to form slightly larger 

 vessels before supplying the epithelium of the gas gland. This 

 process of supplying the glandular epithelium goes on until the 

 whole of the rete mirabile is used up (PI. III. figs. 15-17,), the 

 fine capillaries of the rete always uniting to some extent to form 

 larger vessels before these supply the epithelium. The bladder 

 epithelium, as shown in the figures, becomes enormously thickened 

 by a process of folding during the breaking-up of the rete mira- 

 bile. Posterior to the rete mirabile, which has thus disappeared 

 in supplying the glandular epithelium, this latter itself gradually 

 dwindles (fig. 18) until in the posterior region of the bladder 

 the cavity is lined with simple squamous non-glandular cells. 



The epithelium of the bladder is quite simple in type and 

 essentially resembles the folded epithelium of the Eel, though 

 the folding is much more pronounced. Figure 19 represents the 

 glandular epithelium in the unthickened region, that is, lining 

 any side of the bladder cavity other than that adjacent to the 

 rete mirabile, where, as just stated, the epithelium is much 

 thickened. The folds of the epithelium due to the large capil- 

 laries which push out the epithelium are so deep that we have 

 here, as in Anguilla, distinct ducts fonxied between the folds 

 which contain on occasion large quantities of floccular matter 

 evidently derived from the cells. The thickened epithelium 

 adjacent to the rete mirabile is formed by the great ex- 

 tension of the folds just mentioned, the cells of which often 

 join at intervals, i. e. the folds run together so that the at-first- 

 separate ducts form anastomosing channels before opening into 

 the bladder. The cells forming this epithelium are faintly 

 granular and almost cubical in form, and here and there contain 

 gas bubbles (not shown in the figure) and intracellular capil- 

 laries, but since I have examined these structures in greater 

 detail in other types, I shall not refer to them any further at 

 present. I shall also, and for the same reason, merely mention 

 here the conspicuous opacity of the cytoplasm of the gland cells 

 which comes into immediate contact with a capillary (fig. 19). 



One other fact which is very well shown in my slides of 82/n- 

 gnathus remains to be mentioned, and that is the disintegration 

 of the red blood corpuscles contained in the cajoillaries of the 

 rete mirabile and the gas gland first into spherical globules and 

 ultimately into granular matter. This granular matter resulting 

 from erythrocytolysis is, of course, only found in the blood-stream 

 and is to be carefully distinguished from the granular matter 

 above described as being found in the bladder lumen and gland 



