278 THE SALAMANDER 



The kidneys in both sexes are paired and symmetrical and are 

 very much more elongated than they are in the Frog. Each is narrow 

 and ribbon-like anteriorly and becomes wider and thicker posteriorly. 

 The former portion, called the 'sexual kidney' on account of its 

 association with the gonad in the male (vide infra\ is a true mesone- 

 phros. The recent work of Gray referred to above shows that in 

 Triton the 'sexual kidney' is sharply defined from the posterior 

 portion in its developmental history. He calls the latter the 'defini- 

 tive kidney' and says that in this portion the primary definitive units 

 arise from a set of vesicles distinct from those of the sexual part, and 

 that these primary units eventually serve as collecting ducts for the 

 secondary definitive units which bud off from them. There is thus 

 not only a differentiation of function but also of fundamental struc- 

 ture in the two portions of the kidney. 



It is of course unsafe to assume that the developmental history of 

 the Salamander's kidney is identical with that of Triton, but there is 

 every reason to suppose that it is similar^ particularly as far as the 

 'definitive kidney' is concerned. The 'sexual kidney' is quite different 

 in macroscopic appearance, and hence developmental differences are 

 more likely to be present in this region if anywhere. Ciliated nephro- 

 stomes are present, but show a degenerative tendency in the sexual 

 kidney of the male (Spengel). The glomeruli are easily observed 

 with the aid of a dissecting microscope, either directly in a freshly 

 killed specimen or after injection with Prussian blue. The Mal- 

 pighian bodies of the 'sexual kidney' are very regularly — but not 

 segmentally — arranged in a linear row, while in the 'definitive 

 kidney' the arrangement is necessarily more complex. 



Adrenal bodies are present and appear as small orange patches on 

 the ventral surface of the kidneys in both sexes. They are not, how- 

 ever, confined to the kidneys as they are in the Frog, but may be 

 found anterior to them, as far as the subclavian artery, associated 

 with the sympathetic ganglia. 



In both sexes there is to be found lying in the dorsal mesentery, 

 ventral to the aorta, about 7 mm. posterior to the subclavian artery, 

 a pair of small pear-shaped bodies, looking, at first sight, rather like 

 large sympathetic ganglia, although they vary considerably in size 

 and appearance. They seem to represent the structure described 

 and figured by Leydig (see p. 277), but he found it on the right 

 side and in the male only, whereas that described here normally 

 occurs on both sides and in both sexes. Leydig thought that the 

 structure was connected with Muller's duct, which is certainly not 

 the case. It is, however, richly vascular and is connected with the 



