Physiology, Physiological Chemis- 

 try and Experimental Pathology 

 of the Parathyroid Glands 



SUTHERLAND SIMPSON 



ITHACA 



Introduction 



In attempts by physiologists to determine the functions of any of the 

 endocrine organs or glands of internal secretion, two general methods are 

 employed. 



One is to study the effects, immediate or remote, of the surgical re- 

 moval of the organ in the lower animals, or of its destruction, by accident 

 or disease, in man ; the other is to observe what happens when the gland 

 itself, or a watery, saline, or alcoholic extract of it, is administered intra- 

 venously, subcutaneously, or by mouth. 



The results obtained by either of these methods must be interpreted 

 with caution, however, since it must be remembered that the effect of sud- 

 denly removing an organ in toto may be quite different from that of its 

 gradual disappearance in disease. Because a certain action follows the 

 administration of an extract of any particular gland, it does not necessar- 

 ily follow that this gland, in situ, is continuously furnishing an internal 

 secretion which normally brings about this action ; the extract with which 

 we are dealing may be a postmortem product. In the case of the parathy- 

 roid gland, practically all our knowledge of its functions has been gained 

 by an application of the first of these two methods ; the second has yielded, 

 so far, little or nothing. 



In several cases the attention of the physiologist was first attracted to 

 the organ in question by the clinician. The relationship established by 

 the physician Addison between certain pathological changes in the supra- 

 renal capsules and the group of signs and symptoms first described by 

 him, marked the starting point of the investigations of physiologists into 

 the functions of this organ. The same may be said of earlier studies in 

 the case of the thyroid and pituitary glands. With regard to the parathy- 

 roids, however, the order has been reversed. The knowledge gained by 

 the physiologist, mainly as the result of experimental extirpation, has led 



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