SO URCE 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 
body 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, segmentallv 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 O - 0055 
grms. (oh 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 - 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 w 7 hich 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 grm. 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 x A 1 grms. (less than -gfa 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., r ' Jov.rn. Physiol., Cambridge and 
London, March 1S97, and Proc. Roy. Soc. London, 1897, vol. Ixi. p. 64; and vol. lxii. 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 snprarenals, but contain no medullary tissue. 
4 The proportion of suprarenal capsule to body weight is given by Langlois as from 
Two" to TiWiT m 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. 
