B. A. HOUSSAY 



of adrenalin. (5) Certain hormones can produce an insufficiency by 

 damaging an organ; thus anteropituitary extracts and, in certain 

 cases, those of the thyroid as well, by a repeated action bring about the 

 disappearance of the j8-cells of the islets of Langerhans and produce a 

 pancreatic diabetes, the cause of which could not be deduced by any 

 one not familiar with the previous history. 



METHODS OF STUDY 



Many methods are required to study the endocrine glands and 

 their hormones. 



Morphological. Important data can be obtained by the study 

 of the weight and macro- and microscopic structure of the endocrine 

 organs of different ages and under different conditions, created by 

 extirpation of other organs and injections of hormones. It is also 

 necessary to watch for the initiation and localization of the changes. 



Chemical. These include: {a) a search for and isolation and 

 purification of the hormones by means of a combination of biological 

 assays and chemical methods; {b) a study of the chemical changes 

 and metabolic modifications produced in an animal by the suppression 

 or administration of hormones; {c) action of the hormones on tissue 

 slices or on chemical systems in vitro; and {d) a study of the origin, 

 metabolism, and excretory products of the hormones. 



Physiological, These can be subdivided into experimental and 

 clinical methods. The experimental method includes the study of: 

 {a) glandular insufficiency and restitution through grafting, implants, 

 or administration of either extracts or hormones; {b) hyperfunction 

 induced by the methods already described; {c) measurement of the 

 hormones in the organ, in the blood that comes away from it, in that of 

 the general circulation, or even in the urine. It can also be indirectly 

 measured by finding the amount necessary to substitute for the removed 

 organ (substitution method). It is much safer to measure the hormone 

 secreted by an organ than the amount the organ contains, because the 

 amount secreted does not always vary parallel with the amount present 

 in the organ. 



The clinical study is very valuable: (a) because it furnishes 

 human data and {b) because the disease is a spontaneous experiment, 

 the conditions being sometimes more delicate and varied than the 

 experimental methods can secure. Many endocrine functions have 



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