SO URGE OF THE A CTIVE MA TERIAL OF SUPRARENAL. 957 



organ, has been confirmed in an interesting manner by the observations 

 of Swale Vincent upon the glands of fishes. 1 Elasmobranchs possess 

 two sets of organs, which appear from their structure to represent the 

 suprarenal capsules of other vertebrates ; the one of these, the inter-renal 

 lody of Balfour, lies between the posterior part of the kidneys in the 

 middle line ; the other, the paired bodies of Balfour, forms a series lying 

 on either side, segmentally arranged, on the branches of the dorsal aorta. 

 Teleosts possess only one kind of gland representing the suprarenal ; 

 this in its structure is similar to the inter-renal of Elasmobranchs. As 

 Vincent has shown, the minute structure of the paired bodies of 

 Elasmobranchs resembles that of the medulla of the suprarenal of other 

 vertebrates, while the inter-renal body is similar to the cortex of the 

 ordinary vertebrate suprarenal. 2 The physiological test shows this in a 

 striking manner, for injection of an extract of the paired bodies of 

 Elasmobranchs produces in a marked degree the phenomena which are 

 characteristic of the medulla of the mammalian suprarenal, while extracts 

 of the inter-renals of Elasmobranchs and of the corresponding organs 

 of Teleosts have no such effect. 3 



Dose. One of the most interesting and important facts regarding 

 the material which is yielded by the suprarenals, is the minuteness of 

 the dose which is necessary to produce the results. As little as 0*0055 

 grms. (5J mgrms.) of dried suprarenal is sufficient to obtain a maximal 

 effect upon the heart and arteries in a dog weighing 10 kilos. For each 

 kilogramme of body weight, therefore, the necessary quantity to produce 

 a maximal effect is 0'00055 grms., or little more than half a mgrm. 4 

 The active principle is, however, contained only in the medulla of the 

 gland, not in the cortex, and the medulla in all probability does not form 

 more than one-fourth of the capsule by weight. Of the dried medulla 

 certainly not less than nine-tenths is composed of proteid and other 

 material which is not dialysable, and which otherwise does not conform 

 to the chemical properties which are associated with the active substance 

 of the gland. So that, if we take these facts into consideration, we find 

 that,in order to produce a maximal effect, a dose of not more than fourteen- 

 millionths of a grin, of the active material per kilo, of body-weight 

 is all that is necessary. Now it is certainly true to say that one- 

 fourteenth of this dose will produce some effect, although not perhaps a 

 very large one. We thus arrive at the astounding conclusion, that the 

 active principle of the suprarenal capsules, administered in the pro- 

 portion of not more than one-millionth part of a grm. per kilo, of body 

 weight, which would be equivalent to ysiroTr grrns. (less than ^ of a 

 grain) for an adult man, is still sufficient to produce distinct physio- 

 logical results upon the heart and arteries. 5 



1 Anat. Anz., Jena, 1897, S. 47 ; " Proc. Physiol. Soc.," Journ. PhysioL, Cambridge and 

 London, March 1897, and Proc. Roy. Soc. London, 1897, vol. Ixi. p. 64; and vol. Ixii. p. 176. 



- These homologies were long since inferred by Leydig from a study of their structure 

 (" Fische u. Reptilien," Berlin, 1853), and later by Balfour from a study of their develop- 

 ment (" Comparative Embryology," 1881, vol. ii. p. 549). 



3 It is, however, difficult to avoid contamination with the paired bodies in extracting 

 the inter-renal. Vincent has also found, in an experiment which is not yet published, that 

 an eel will survive, for some weeks at all events, removal of the glands which appear to be 

 the only representative of the mammalian suprarenals, but contain no medullary tissue. 



4 The proportion of suprarenal capsule to body weight is given by Langlois as from 

 TTJHnr to TT^TRr in the dog. 



5 The chemical nature of this active principle is still obscure, since, in spite of much work 

 on this subject, it has never been isolated. The history of this has been already dealt 

 with by Halliburton, along with the chemistry of the suprarenals, on pp. 90-92. 



