290 LIFE : OUTLINES OF GENERAL BIOLOGY 



lating medium has resulted from the investigations of the last 

 thirty years on the secretions of the ductless glands; and to the 

 re-consideration of these we must now pass. 



INTERNAL SECRETIONS.— Claude Bernard seems to have been 

 the first physiologist to realise with clearness the importance of 

 the "ductless glands" or glands of internal secretion. He refers 

 to the secretion produced by such organs as the thyroid body, 

 the suprarenal capsules, and the spleen; but it should be noted, 

 perhaps, that he applied the term "internal secretion" to grape- 

 sugar, which passes, as he showed, from the liver-cells into the 

 blood. This use of the term would not be accepted to-day, for it 

 is now restricted to chemical agents that have a specific effect on 

 certain tissues or processes; it does not include general nutritive 

 material, or the mere waste-products, or the products of glands 

 with ducts. 



But Claude Bernard's suggestion did not attract much attention, 

 and more stimulating to research was Brown-Sequard's demon- 

 stration of the tonic effects of testicular extract — a scientific 

 vindication of ancient medical prescriptions, such as the use of 

 the stag's testes as an aphrodisiac. But Brown-Sequard was led 

 by his experiments with testicular extract to a theory almost too 

 generalised to mean much; he maintained that all tissues contribute 

 to the blood something or other that is specific and important. 

 This was too general a return to the old idea of a consensus partittm, 

 a functional correlation of the body effected by diffused "humours" ; 

 but even in this vague notion there was sound sense. 



Some interesting historical notes are given by Dr. Swale Vincent 

 in his scholarly treatise. Internal Secretion and the Ductless Glands 

 (3rd ed., London, 1924). Thus as far back as 1775 Th^ophile de 

 Borden spoke of each organ as the source of a "humeur particulit re", 

 which exerts an influence on the body generally; in 1801 Legallois 

 discussed the relation between the different secretions (from all 

 glands, however) and the varying composition of the venous blood; 

 in 1852 W. B. Carpenter spoke definitely of the contributions 

 made to the blood by the "vascular glands" (e.g. thyroid and supra- 

 renal), along with which he included fatty tissue and the spleen. 

 Very important, though forgotten till unearthed by Biedl, was 

 an experiment made in 1849 by Berthold of G5ttingen. He excised 

 testes from young cockerels and grafted them on the wall of the 

 intestine, with the result that the cockerels did not develop, as 

 castrated males usually do, into capons, but grew into normal cocks. 

 The student will observe the increase of definitencss and precision 

 that so often marks the emergence of a speculative idea into a 

 substantial discovery. The general idea of correlation of the body 

 is very old — familiar, for instance, to St. Paul, who speaks of the 



