120 W. F. R. WELDON. 



side a small, lobulated, apparently glandular body, whose 

 structure is not so well known. 



Each of these bodies is, in Bdellostoma Forsteri, from 

 20 to 25 millimetres long, and from 5 to 7 mm. broad ; looked 

 at with a simple lens, or with the naked eye, it is seen to 

 consist of several small lobuli, which project into the cavity of 

 the pericardium on the one hand, the whole gland being con- 

 nected on the other with the connective-tissue adventitia of a 

 great vein — the gland of the right side with the adventitia of 

 the portal vein, that of the left with the anterior cardinal. In 

 PI. XII, fig. 1, an attempt has been made to represent the 

 appearances seen on looking at the gland from the interior 

 of the pericardium. 



Johannes Miilleri described these organs as consisting ol 

 ''very small elongated lobuli, which are attached to blood- 

 vessels, and are united with one another by loose connective- 

 tissue. Each lobulus or cylinder consists .... of a double 

 row of cylindrical nucleated cells, like those of a columnar 

 epithelium, the two rows of cells fusing with one another at 

 the base of each lobulus. Between them run blood-vessels." 



No further statements on the subject were published till 

 1875, when Prof. Wilhelm Miiller ^ gave an account of some 

 observations made on Myxine glutinosa. In this animal 

 Prof. Miiller found that the bodies in question were con- 

 nected each with the segmental duct of its own side, 

 while the " double rows of cells " of Johannes Miiller he found 

 to be segmental tubules of a perfectly normal character, com- 

 municating by ciliated funnel-shaped openings with the peri- 

 cardium, and provided with glomeruli. 



The obvious inference was that these organs represented that 

 anterior part of the kidney which is so well developed in many 

 larval Icthyopsida, and which is known as the " pronephros," 

 or " head kidney.'' 



Professor Miiller, however, expressly states in his paper that 

 his investigations were made upon very young animals. 



' Loc. cit., part iii, pp. 7, 8. 



' « Jenaische Zeitschrift/ ix, 1875, pp. 111—113. 



