PLATE I 



Microphotographs of transverse sections through 

 the swimbladder. 



Fig. i. Vinciguerria nimbaria; section cut towards the posterior end 

 of the swimbladder between the rete and gas-gland ( x 150). Note 

 the artery-vein pairs (each an association of a large and small 

 vessel) running to the gas-gland and the undulating appearance 

 of the fibres in the submucosa. 



Fig. 2. Section through the regressed swimbladder of Cy clot hone livida 

 ( x 300). Note the capillaries of the regressed rete mirabile and 

 the regressed cells of the gas-gland (mainly to be seen in the upper 

 right half of the section. See also text fig. 34). 



Fig. 3. Section through the rete of Polyipnus laternatus ( x 130). Note 

 the section cut through the by-pass branch of the retial artery at 

 the top of the photograph. 



Fig. 4. Enlarged part of Fig. 3 ( x 580). The ' triangle ' of nuclei (at 

 about 7 o'clock) in Fig. 3 will be again seen in this figure. The 

 larger capillaries in this section belong to the venous part of the 

 retial circulation. 



