SCIENCE 



[Vol. LV, No. 1435 



count of their astonishing and novel revela- 

 tions, attracting the attention not only of 

 scientific workers in biology and medicine but, 

 and perhaps to too great an extent, also of the 

 laity. Important as a knowledge of these 

 incretions is for an understanding of bodily 

 and mental states, there is some danger, I think, 

 of over-emphasis and of disproportionate 

 prominence. Popular articles and treatises on 

 endocrine subjects too often assume what is 

 mere conjecture, or wild speculation, to be 

 established as fact and reveal a tendency to 

 exploitation that must sooner or later be fol- 

 lowed by disappointment and disillusionment. 

 There is, I fear, some danger that even scien- 

 tific endocrinology may, temporarily at least, 

 be brought into undeserved discredit. It would 

 seem especially desirable, therefore, that those 

 who write or speak upon the subject should 

 discriminate carefully between fact and fancy. 

 Every effort should be made rigidly to control 

 hypotheses by accurate observation and careful 

 experiment, for only thus can an orderly ad- 

 vance in knowledge be assured. 



Though an incretory function has been 

 ascribed to many organs of the body, the prin- 

 cipal incretory organs, those whose function is 

 best understood, are seven in number: (1) the 

 thyroid gland, (2) the parathyroid glands, 



(3) the hypophysis cerebri, or pituitary gland, 



(4) the epiphysis cerebri, or pineal gland, 



(5) the suprarenals (consisting of two parts of 

 entirely different functions, (a) the medulla or 

 chromaffine portion and (6) the cortex or inter- 

 renal portion), (6) the islands of Langerhans 

 of the pancreas, and (7) the interstitial tissue 

 of the gonads (ovaries and testicles) or so- 

 called "puberty gland." 



There is evidence that each of these organs 

 yields an internal secretion that, distributed 

 through the blood, exerts important chemical 

 influences upon other, more or less distant, 

 organs and tissues. Some of these influences 

 have been definitely determined, but it will 

 doubtless be a long time before all of them will 

 be well understood. The knowledge that has 

 been gained concerning the thyroid, the pitu- 

 itary, and the suprarenals gives pix)mise, how- 

 ever, that steady research will gradually en- 

 large our information regarding the influences 

 exerted by each of the incretory glands. 



The chemical substances contained in the 

 incretions have been called "hormones" and the 

 determination of the precise chemical constitu- 

 tion of these hormones sets fascinating tasks 

 for the biochemist. That the chemical consti- 

 tution of some endocrine products may be 

 closely approached, if not definitely estab- 

 lished, has been shown by researches upon 

 epinephrin (from the medulla of the supra- 

 renal gland) and upon iodothyrin and thyroxin 

 (from the thyroid gland). Studies of concen- 

 trated functionally potent extracts from other 

 glands may before long reveal the chemical 

 nature of other hormones; I have in mind, 

 especially, studies of so-called "pituitrin" 

 ( hyjjophyseal extract) and of so-called insulin 

 (extract of the islands of Langerhans of the 

 pancreas). Clues as to the chemical nature of 

 the hormones of the parathyroids, the pineal 

 body, the interrenals and the gonads wll prob- 

 ably be more difficult to obtain. Biochemical 

 reseai'ches to establish the precise nature of the 

 single hormones are extraordinarily important 

 and should be vigorously prosecuted in order 

 that experimental studies of hormone influ- 

 ences may he more systematically, exactly and 

 intelligently pursued. 



THE BETTER-KNOWN ENDOCEINOPATHIES 



Our knowledge of endocrine functions has 

 been variously derived, partly through 

 keen clinical-pathological observations, partly 

 through experimental work upon animals (sur- 

 gical removal of single organs; organ trans- 

 plantations; injections of organ extracts or of 

 isolated hormones). Before discussing the 

 relations of the endocrine organs to heredity 

 and development, it may be helpful briefly to 

 refer to a few of the classical clinical syn- 

 dromes that are now justifiably believed to be 

 endocrinopathic in origin. Time will not per- 

 mit me to refer to more than a few of these, 

 but those chosen will serve as illustrative 

 paradigms. 



I may cite first two characteristic clinical 

 syndromes met with in association with disease 

 of the thyroid gland, namely, exophthalmic 

 goitre and mysa;dema. 



In the former, known also as Graves' disease 

 or Basedow's disease, we observe, in typical 

 instances, a markedly enlarged pulsating thy- 



