SUPRAEBNAL BODIES IN PISHES. 77 



head-kidney absent in LoiMus fiscatorms and Orthagoriscus mola. Other authors 

 have added some few more species, see above, also summary below. A few detailed 

 illustrations will suffice. 



Oyclopterus lumpus. — I have particularly examined the kidney of this species. It 

 will be seen (PI. XIII. fig. 40) that it has a peculiar shape. 



At its anterior extremity are two dark red spherical masses of tissue, only attached 

 to the rest of the kidney by connective tissue. On microscopical examination these 

 are found to consist of an extremely vascular lymphoid tissue, with no trace of urinary 

 tubules or Malpighian bodies i. 



The divided portion of the kidney on each side is represented by two very thick 

 masses nearly half the total length of the kidney (fig. 40). 



I find that almost the anterior third of this part, as well as the dark red bodies in 

 front, is composed entirely of lymphoid tissue. As one approaches the junction of the 

 anterior and middle thirds of this part of the kidney, one or two tubules make their 

 appearance in the central portion of the section. In the middle third tubules are 

 more frequent, while in the posterior third the appearance is almost that of " body- 

 kidney " generally. 



So that we have in Cyclopterus a well-developed lymphoid head-kidney, with an 

 anterior part completely constricted off. This constriction may possibly throw some 

 light upon other masses of lymphoid tissue which one finds in the neighbourhood of 

 the kidney in Elasmobranchs as well as in Teleosts. 



With regard to Lojjhius piscatorius, which was supposed by Hyrtl to have only a 

 head-kidney, I find with Balfour tubules and Malpighian bodies in all parts of the 

 kidney-mass except the extreme anterior end, where Malpighian bodies are absent. 

 Here, too, there is more adenoid tissue than elsewhere, and it appears more probable 

 that the whole kidney is contracted longitudinally, and that the lymphoid remains of 

 the pronephros have been encroached upon by the mesonephros than that the whole 

 of the ordinary excretory organ has been lost, and the pronephros has remained as the 

 functional kidney. 



In Anguilla anguilla I found in a specimen 68 cm. long, with a total length of 

 kidney of 25 cm., that exactly the anterior three-quarters of the ununited portion of 

 kidney on each side was entirely lymphoid, i.e., half the total length of the kidney. 

 At the mid-point of the kidney-length tubules begin to appear and rapidly increase in 

 number till the normal secreting structure is reached. 



In the Sturgeon the whole of the part h.k. (PI. X. fig. 8) as far as the dotted line is 

 purely lymphoid. There is also a small area of lymphatic tissue at the extreme hinder 

 end of the kidney. 



In the Sunfish all parts of the kidney contain urinary tubules, even the extreme 



' [This structure corresponds to that of a " hosmo-lymph gland " (see Vincent and Harrison, Journ. of Anat. 

 and Phys., Jan. 1897).— S. V., 10. 1. 97.] 



