DEVELOPMENT OF ELASMOBRAXCH FISHES. 241 



alveoli, and is formed of irregularly polygonal cells ; and though 

 it is difficult to give an estimate of their size on account of 

 their in-egularity, '021 Mm. may be taken as probably about 

 the diameter of an average cell. The character of the cortical 

 and medullary cells is nearly the same, and the cells of the two 

 strata appear rather to differ in shape than in any other essen- 

 tial point. The protoplasm of both has a markedly yellow 

 tinge, giving to the suprarenal bodies a yellowish brown colour. 

 The nuclei are small compared to the size of the cells, beino- 

 about '009 Mm. in both cortical and medullary cells. In the 

 anterior suprarenal body there is a less marked distinction 

 between the cortical and the medullary layers, and a less pro- 

 nounced yeUow coloration of the whole, than in the posterior 

 bodies. The suprarenal bodies are often partially or completely 

 surrounded by a lymphoid tissue, which is alluded to in the 

 account of their development. 



The most interesting features of my sections of the anterior 

 bodies are the relations they bring to light between the sympa- 

 thetic ganglia and the suprarenal bodies. In the case of one of 

 the posterior suprarenal bodies, a small ganglion is generally 

 found attached to both ends of the body, and invested in the 

 same sheath ; in addition to this a certain number of ganglion 

 cells (very conspicuous by their size and other characters) are 

 to be found scattered through the body. In the anterior supra- 

 renal bodies the development of ganglion cells is very much 

 greater. If a section is taken through the region where the 

 large sympathetic ganglion (already mentioned) is attached to 

 the body, one half of the section is composed mainly of sympa- 

 thetic ganglion cells and nerve fibres, and the other of supra- 

 renal tissue, but the former spread in considerable numbers into 

 the latter. A transverse section through the suprarenal body in 

 front of, or behind this point, is still more instructive. One 

 of these is represented in PL xviii. fig. 7. The suprarenal tissue 

 is not inserted, but fills up the whole space within the outline 

 of the body. At one point a nerve (n) is seen to enter. In 

 connection with this are a number of ganglion cells, the exact 

 distribution of which has been reproduced. They are scattered 

 irregularly throughout the suprarenal body, but are more con- 

 centrated at the smaller than at the larofe end. It is this small 



