June 25, 1897.] 



SCIENCE. 



967 



ered of greater physiological value. Fur- 

 ther, it needs to-day little argument to 

 support the view that such power as these 

 physiologically active glands possess is due 

 to definite chemical compounds elaborated 

 by the glands as products of their individual 

 secretory or metabolic activity. As with 

 other glands having more obvious functions, 

 the secreting cells plainly manufacture cer- 

 tain specific products, but in the case of the 

 internal secretions these products find their 

 way into the blood and lymph, by which 

 they are distributed throughout the body, 

 and thus made available either in con- 

 trolling or regulating the general nutrition 

 of the economy or to serve some more specific 

 purpose of equal importance for the welfare 

 of the organism. This being so, it is equally 

 probable that in the general and specific 

 metabolism going on in all the tissues and 

 organs of the body the various products 

 formed and absorbed by the blood and 

 lymph may contribute somewhat to the 

 welfare of the body prior to their excretion. 

 In its broadest sense, therefore, internal 

 secretion must be looked upon as something 

 common to all active tissues, the ordinary 

 katabolic products of both circulating and 

 morphotic proteids, for example, no doubt 

 exerting some physiological action during 

 their transit from the place of their forma- 

 tion to the organ which serves for their ex- 

 cretion. It is well, perhaps, to give full 

 recognition to this possibility, for physio- 

 logical equilibrium in the broadest sense is 

 clearly dependent upon the harmonious 

 action of a large number of related parts, 

 and experiment only can determine, and 

 perhaps then imperfectly, how far the 

 products of one gland or tissue are essential 

 for the well-being of the whole. We know, 

 however, that certain organs with the 

 products they elaborate can be dispensed 

 with, while the removal of other organs in- 

 volving no greater surgical interference is 

 quickly followed by marked disturbances 



and later by death. Czerny had no diffi- 

 culty in removing the stomach from dogs, 

 the health of the animals remaining unim- 

 paired when the oesophagus was properly 

 joined to the intestine. Similarlj', Schafer 

 and Moore* have recently shown that both 

 parotids and both submaxilliary glands may 

 be removed from the dog without any dis- 

 turbance of nitrogenous metabolism, or 

 without any apparent efi"ect upon carbohy- 

 drate digestion. Evidently these glands do 

 not possess any intrinsic internal secretion 

 necessary to the life of the animal or having 

 any important action on the metabolic pro- 

 cesses of the body. If they do furnish an 

 internal secretion it obviously must be one 

 common in function to that supplied by 

 some other organ. In the present discus- 

 sion, therefore, we may advantageously 

 limit the term ' internal secretion ' simply 

 to those specific products which, being 

 manufactured in certain definite glands, are 

 plainly endowed with well-defined physio- 

 logical action. 



Let us first consider the thyroid gland 

 upon which more work has been done than 

 upon any other similar structure. Dating 

 from 1883, when Kocher and Eeverdin pub- 

 lished their well-known observations on the 

 effects of thyroidectomy in the human sub- 

 ject, it has gradually become apparent that 

 there are two distinct ways in which the 

 effects of the operation may be manifested.-}- 

 Thus, in some animals, as in most carnivora, 

 complete removal of the thyroidal tissue is 

 followed by a rapid development of symp- 

 toms indicating a marked irritation of the 

 nervous and muscular sj'stems as mani- 

 fested by tetanus, epileptiform convulsions, 

 etc., terminating in death. In other cases 



*Proceed. Physiol. Soo ; Journal of Physiol. Vol. 

 19, No. 4. 



t Compare Koos: Ueber die Einwirkung der Schild- 

 driise auf den Stoffwechsel nebst Vorversuchen iiber 

 die Art der wirksamen Substanz in derselben. Zeitschr. 

 £. physiol. Chem. Band 21., p. 19. This paper con- 

 tains numerous references. 



