SUPRA-RENAL CAPSULES. 83 



are continuous the transparent, brittle, and sometimes pigmented and branched cells of the 

 medulla. Both cortex and medulla are richly supplied with blood-vessels, the distribution 

 of which follows that of the trabeculae. A large number of nerves and nerve-ganglia exists 

 in the organs. 



PREPARATION. It is best to employ the capsules of large mammals, e.g. of the ox, or, 

 best of all, the horse. If these cannot be obtained, use the supra-renals of a guinea-pig. In 

 the case of the human organ, it must be obtained as fresh as possible, (a) Harden pieces in 

 Miiller's fluid for three weeks, or in chromic acid and spirit mixture for two weeks, and then 

 transfer them to spirit. Make transverse sections, and stain them with logwood, and mount 

 them in dammar. 



(If) Osmic Acid. Place pieces about the size of a pea in a quarter per cent, osmic acid for 

 eight hours, and complete the hardening in spirit. This method gives excellent results, but it 

 must be remembered that the osmic acid is apt to fix only the outer layers. 



EXAMINATION (L). Observe the capsule and its trabeculae, also the cortex with its 

 three zones and the medulla, and note the partially pigmented cells (PL XX., Fig. 4). (H). 

 Study the cylinders of cells, and compare them with the foregoing description (PI. XX., 



Fig- 5). 



Study the injected specimen, and note the distribution of the blood-vessels. 



M 2 



