96 THE POPULAR SCIENCE MONTHLY 



extract by Murray and Howitz in 1893. In 1884, Sir Victor Horsley 

 produced an experimental myxoedema by removal of the thyroid in 

 monkeys, which were found to survive much longer than dogs. It was 

 also found by Allara (1885), Ewald (1890) and others, that experi- 

 mental thyroidectomy is negative in birds, rodents and herbivorous 

 animals, and that, both in animals and man, operative myxoedema is 

 produced less frequently as age advances. In 1888,^^ Sir Felix Semon, 

 in an important collective investigation, showed that cretinism, myxoe- 

 dema and operative myxoedema (cachexia thyreopriva) are one and 

 the same. In 1889, Brown-Sequard, then aged seventy-two, found 

 himself vastly rejuvenated as to general health, muscular power and 

 mental activity, by the subcutaneous injection of testicular extracts, 

 the active principle of which Poehl, the Eussian physiologist, holds to 

 be the substance spermin (CgHi^JSTa). These experiments of Brown- 

 Sequard easily lent themselves to ridicule, but he followed them up, 

 even to the extent of giving pituitary extract for disease of that organ 

 (1893), and it was his work upon these extracts which led him to formu- 

 late the following statement of the old Bordeu theory of internal 

 secretions : 



All the tissues, in our view, are modifiers of the blood by means of an inter- 

 nal secretion taken from them by the venous blood. From this we are forced to 

 the conclusion that, if subcutaneous injections of the liquids drawn from these 

 tissues are ineffectual, then we should inject some of the venous blood supplying 

 these parts. . . . We admit that each tissue and, more generally, each cell of the 

 organism secretes on its own account certain products or special ferments which, 

 through this medium, influence all other cells of the body, a definite solidarity 

 being thus established among all the cells through a mechanism other than the 

 nervous system. . . . All the tissues (glands or other organs) have thus a spe- 

 cial internal secretion and so give to the blood something more than the waste 

 products of metabolism. The internal secretions, whether by direct favorable 

 influence, or whether through the hindrances of deleterious processes, seem to 

 be of great utility in maintaining the organism in its normal state.23 



As theory goes, nothing new has been added to the doctrine of 

 internal secretions since Brown-Sequard stated it in this form in 1891. 

 In his essay on "Variation" (1868) Darwin seems to have had a glim- 

 mering of the idea when he stated that gemmules are transported from 

 all parts of the body to the ovum to insure their reproduction (pan- 

 genesis), and the Bayliss-Starling doctrine of the "hormones" or 

 chemical messengers, as we shall see, is not essentially different from 

 that of Bordeu and Brown-Sequard. 



From the time of Brown-Sequard on, experimental investigation of 

 the subject moved so rapidly and in so many different directions that 

 the general trend of the theory became obscured or lost in the details of 

 controversy. And further obfuscation was brought about by the con- 

 stant succession of dissolving views of the subject of carbohydrate 



22 Tr. Clin. Soc, London, 1888, Suppl. to Vol. XXI. 



23 Brown-Sequard, Arch, de physiol, norm, et path., Paris, 1891, 5 s.. III., 506. 

 Cited by Gley. 



