The Comparative Histology of the Suprarenal Capsules. 307 



stränge" and "Zwischenstränge" to cortex and medulla respectively in 

 birds, but it is difficult to find terms which are applicable to the two 

 kinds of tissue throughout Vertebrates. For this reason it is better 

 to retain the names cortex and medulla, always bearing in mind that 

 they are quite misnomers in all animals below mammals. 



The above-named observer made the very interesting discovery 

 that there are intermediate forms of cells between the ganglion cells 

 of the sympathetic nervous system and the proper cells of the supra- 

 renal medulla. Braun (loc. cit.) had previously described such in 

 Reptilia. I have indicated above that these are to be found in the 

 medullary glands of Elasmobranch fishes, and I can corroborate the 

 statement of Rabl with regard to Aves. 



IX. Mammalia. 



In the Mammalia the two separate glands of which the suprarenal 

 capsule is composed are not irregularly mixed up as in birds, but the 

 medulla is placed internally, being completely surrounded by cortex. 

 Indeed it is only in Mammals that these terms are appropriate to 

 the two portions. 



If one cuts across a fresh suprarenal capsule of any Mammal the 

 cortex and medulla are always quite readily distinguishable from one 

 another. But there are wide differences in the general appearance of 

 the section in different species. Thus in some cases the cortex is 

 narrow and the medulla extensive, but in most cases the opposite is 

 the case, and the rule is that by far the greater bulk of the capsule 

 is made up of cortex. The guinea-pig has proportionately a large 

 medulla. 



In tint too there is considerable variation; thus in the sheep there 

 is a yellowish white medulla, surrounded by a dark red cortex. In 

 the dog there is a dark pink medulla and an ochre-yellow cortex. The 

 rabbit has a very slight core of a greyish medulla surrounded by a 

 yellow cortex. In the guinea-pig much of the chromogen in the 

 medulla is developed into a pigment, and the substance appears dark 

 brown or purple when cut across. 



These differences are undoubtedly associated in some way with 



20* 



