302 S. Vincent, 



and tlie Opliidia the suprarenal body is situated between the postcaval 

 vein and the reproductive gland (ovary or testis as the case may be). 

 The position in the Chelonia is only apparently different, because in 

 this order the kidneys and reproductive organs are on about the same 

 antero- posterior level. I have not been able to examine any of the 

 Crocodilia. 



The histological structure of the suprarenal capsules in the Eeptilia 

 closely resembles that in the Amphibia. The cortical substance (which 

 constitutes by far the greater part of the gland) consists of curved, 

 irregular, branching, and interlacing columns of cells, about 50 /< 

 thick and reaching a length of 120 ,« (PI. XVIII. fig. 13), consisting 

 most often of a double row (as seen in section), but sometimes having 

 three or even four tiers. The cells are 20 — 26 /.i in length and about 

 8 — 10 /< in width and their protoplasm is very distinctly reticulated 

 (eo, PI. XVin. fig. 13); near the centre of each is a large rounded or 

 oval nucleus (n) about 1 f.ix "ò (.l or about 5 f^i in diameter, with a 

 marked nuclear network {n. net) and nucleoli. 



The medullary masses (PI. XVni. fig. 13, me) are of various 

 sizes and shapes, distributed through the gland. The greater part of 

 the medulla forms a layer along the dorsal aspect of the organ, but 

 groups of five, six, or more cells are found in different regions of the 

 organ. There are also smaller groups (see, PI. XVIII. fig. 13) or 

 even occasionally isolated single cells. The cells are larger than those 

 of the cortex, as also are the nuclei; the cell protoplasm is very 

 distinctly granular, the granules being of large size, rounded, and regu- 

 larly distributed throughout each cell {g. p., PI. XVIII. fig. 13). They 

 become very deeply stained with haematoxylin if the tissue has been 

 hardened in alcohol, but brown if in Miiller's fluid. The haematoxylin 

 in the latter case only stains the nucleus, leaving the cell -granules 

 brown. 



Between the columns of cells are blood-spaces lined with a vascular 

 epithelium, i. e. capillaries (PI. XVIII. fig. 13 i). In some parts the 

 cell -columns are arranged in a radiating manner round one of these 

 large blood-spaces, just as one sometimes finds in the internal body of 

 Elasmobranchs (vide supra pag. 291). 



