CH. xxill.] SUPRA-RENAL CAPSULES. 335 



Brown-Sequard attracted much attention at the time they were per- 

 formed, but were almost forgotten until quite recently, when they 

 were confirmed by Abelous, Langlois, Schafer, and others. The 

 effects on the muscular system are the most marked results both 

 after removal of the capsules and after injection of an extract of the 

 glands. The effect of injecting such an extract on the voluntary 

 muscles is to increase their tone, so that a tracing obtained from 

 them resembles that produced by a small dose of veratrine, 

 namely, a prolongation of the period of relaxation. The effect 

 on involuntary muscle is equally marked ; there is an enormous 

 rise of arterial blood-pressure due chiefly to a contraction of the 

 arterioles. This is produced by the direct action of the extract 

 on the muscular tissue of the arterioles, not an indirect one 

 through the vaso-motor centre. The active chemical substance 

 in the extract that produces the effect is either the reducing 

 substance or chromogeu alluded to above, or some other substance 

 united to it; it is confined to the medulla of the capsules, and 

 is absent in cases of Addison's disease. 



The capsules, therefore, form something which is distributed to 

 the muscles and is essential for their normal tone ; when they 

 are removed or diseased the poisonous effects seen are the result 

 of the absence of this internal secretion. 



Some physiologists have considered that the substance which produces 

 these effects is allied to pyrocatechin ; this, however, is incorrect ; it is more 

 probable that the active material is alkaloidal in nature, possibly allied to 

 piperidine or nicotine, both of which substances produce a large rise of 

 blood-pressure. Abel states he has succeeded in isolating the alkaloid ; he 

 has named it epi/iejjh riiie. v. Fiirth has separated another body which he 

 calls xii jiriin nine. It is extremely doubtful if either of these materials 

 is the active substance ; for Moore has shown that a millionth part of 

 a gramme of dried supra-renal will produce an effect on blood-pressure, 

 so a very small contamination of any so-called pure material would vitiate 

 the results. 



Whether this discovery will lead to the same important 

 practical results as in the case of the thyroid and myxcedema 

 must be left to the future to decide. There is already some 

 evidence to show that injection of supra-renal extract is beneficial 

 in cases of Addison's disease. 



There are some points of interest in the development and 

 comparative physiology of the supra-renals. In mammals the 

 medullary portion is developed in connection with the sym- 

 pathetic, and is at first distinct and outside the cortical portion 

 which is developed in connection with the upper part of the 

 \Yollttian body ; it gradually insinuates itself within the cortex 

 (Mitsukiri). In elasmobranch fishes the supra-renals consist 

 throughout life of separate portions ; one the inter-renal body is 



