SUPEAEENAL BODIES IN EISHES. 69 



the main chain of the sympathetic, they have become connected with it in a remark- 

 ably intimate manner ^. 



2. GANOIDEI. 



Strtjctuee of the Supraeenal Bodies op the Sturgeon.— I have examined some of 

 these bodies after putting them quite fresh into 1 o/^ osmic acid for twenty-four 

 hours, and then cutting in gum. They were stained quite black to the naked eye, and 

 on cutting and examining microscopically their alveolar structure was obvious. 



If examined immediately in Farrant's fluid, the alveoli appeared to be filled with 

 mulberry-masses of material most probably of a fatty nature, as they had taken a deep 

 brown stain with osmic acid, so that the cell-outlines were not to be made out. 



If, however, the sections were passed through turpentine or Canada balsam, the 

 structure was beautifully shown (PI. XIV. fig. 44). The rounded or elongated oval 

 alveoli (50-60 ^ in diameter, or even 100 ^u long by about 60 ^, broad) are bounded by 

 bold thick walls, averaging .3 ^t in thickness (al.w.), and the cell-outlines were admirably 

 preserved (x). The preponderating shape of the cells was round or oval, and in some 

 parts they are seen to overlap, as the section was thick enough to contain several layers (x). 

 In other parts the cells are more polyhedral or irregular. Like the alveoli, they vary 

 somewhat in size ; their average diameter is about 20 fx. The nuclei (n.) are deeply 

 stained and somewhat irregular in shape, having a diameter of 3-6 /t. The protoplasm 

 is very finely granular as a rule, occasionally more coarsely granular -. There are small 

 nerve-ganglia in connection with some of the bodies. 



' As for the meaning of the two kinds of body present in the Elasmobranohs and of one only in Teleostei 

 and Ganoids there are two alternative theories. 



One is that the two kinds of structure are both represented in the higher Vertebrates, but that the paired 

 bodies have disappeared in Teleosts. 



The other view is that the paired bodies in Elasmobranohs are the remains of former more important bodies, 

 while in higher forms they disappear altogether. In favour of this it may bo urged that their nerve-supply is 

 quite disproportionate to their size and apparent importance, and possibly represents the persistence of a nerve- 

 supply suited to a former larger structure. 



As to which of these is the correct view I cannot at present be certain, but on the whole perhaps the usual 

 view is the most probable, viz., that in Elasmobranchs the paired suprarenals and the interrenal correspond 

 respectively to the meduUa and the cortex of Amphibians, Reptiles, Birds, and ilammals. 



There is not much diiSculty in recognizing that the interrenal of the Cartilaginous Fishes corresponds to the 

 cortex of higher Vertebrates, but it is far from easy to imagine that the masses of protoplasm with scattered 

 nuclei which constitute the paired bodies in Elasmobranchs are really homologous with the branched granular 

 ceUs of the medulla of higher Vertebrates. 



' When the suprarenals of the Sturgeon are hardened, double-stained in bulk, and cut in paraffin, they do 

 not show nearly such a distinct alveolar arrangement as do those treated fresh with osmic acid. The larger 

 oval nuclei show a very distinct nuclear network and a large darkly-stained nucleolus centrally placed. In 

 other cases only dark nuclear granules of various sizes are to be made out. The cells appear for the most part 

 made up of a variable number (5-6) of vesicles, from which evidently the fat has been dissolved by this mode 

 of preparation. The cells of the body have shrunk to some extent, so as to leave spaces of variable extent 

 between them. 



