SOURCES OF INFORMATION 17 



in connection with the fattening of animals for slaughter. But 

 the older and more obvious belief, that the somatic and psychic 

 modifications resulting from castration were due to a change in 

 the balance of the bodily secretions, was, as we have already 

 seen, more and more undermined by advances in anatomy and 

 physiology. With the knowledge of the intimate relationship 

 to the nervous system in which the individual organs stand, the 

 theory of nervous correlation became firmly established, and the 

 results of castration were regarded simply as signs of the changed 

 activity of the nervous system. 



A closer study of the structure of the individual organs led 

 to a better knowledge of their specific functions, but threw little 

 light upon internal secretory activity, even in the case of what 

 were known as the ductless glands. 



The first fact in connection with these mysterious organs 

 to receive experimental proof, was the discovery that the supra- 

 renal capsules are indispensable to life, and this we owe to human 

 pathology. It is to the undying credit of Thomas Addison (1855) 

 that he connected a pathological condition observed by him in 

 man with a disturbance- of function of the suprarenal capsules. 



The results of human pathology, especially the comparison 

 of the clinical signs with the post-mortem findings, have in other 

 directions supplied the most valuable evidence in favour of the 

 doctrine of internal secretion. Instances are afforded by myx- 

 cedema on the one hand and by exophthalmic goitre and 

 acromegaly on the other. These pathological conditions have 

 supplied facts concerning the physiology of the thyroid and 

 pituitary glands, the value of which is incalculable. In Addison's 

 disease and myxcedema, the normal processes become destructive 

 or generally pathologically hypoplastic, whereby a decrease is 

 brought about in the activity of certain organs, which manifests 

 itself in pathological signs. In Graves's disease, on the other 

 hand, and to a certain extent in acromegaly also, there is excess 

 of activity on the part of the thyroid and pituitary glands, and 

 these diseases may be taken as classic examples of hyperfunction 

 by an internal secretory organ. 



It is certain that in clinical medicine we have an almost 

 inexhaustible source of knowledge, for we find that the careful 

 observation of clinical signs when taken in conjunction with the 

 anatomical findings, continually discloses fresh chemical relation- 

 ships between the different organs. Thus, the form of pituitary 

 disease described by A. Frohlich in 1901, under the name of 

 dystrophia adiposogenitalis, revealed facts regarding the rela- 

 tionship of the pituitary gland to metabolism which were entirely 

 new. 



Operative surgery in man has not only contributed largely 

 to our knowledge (cachexia strumipriva and tetany following the 

 extirpation of the thyroid), but in doubtful cases it frequently 



