380 B. F. KINGSBUEY 



the general metabolism, particularly 'growth metabolism' as 

 centering in the development of the reproductive phase. 



In this origin out of structures of a different adaptative value, 

 in all cases where we may follow it and where the genetic signifi- 

 cance is not still too obscure, there appears to be an element of 

 regressive change present; differentiations of one character, 

 either in the individual or in the race, have disappeared and are 

 replaced by the endocrine organs, and herein lies possibly the 

 hint of a reason for the peculiar correlation of the structures so 

 derived (i.e., the endocrine organs) with the general bodily growth 

 and metabohsm. As I have said elsewhere in discussing the 

 question of the significance of the interstitial cells (Kingsbury 

 '14, p. 81): "The assumption that the end-products of meta- 

 bolism may stimulate growth (and metabolism) is not I beheve 

 opposed to the facts of general physiology, but rather the reverse. 

 As applied to the endocrine organs in general, the suggestion 

 has three sides; (a) that the end-products of their metabolism 

 have a marked stimulator}^ effect on bodily growth (and metabo- 

 lism) ; this would seem more or less a restatement that they are 

 endocrine organs; (b) that the end-products of growth metabolism 

 should peculiarly affect their growth; and (c) as a correlary of 

 (b) that abnormal bodily metabolism should be associated with 

 an abnormality of growth in these structures. 



That the suggestion convej^ed is, in its bearings, broader 

 than the more specific problem of the endocrine organs is obvious 

 on the face of it. In an earlier portion of this paper there is 

 briefly discussed the question of a possible correlation with 

 regressive change of the connective tissue and of the blood-form- 

 ing cells. On the pathological side, the problems of the nature 

 of the inflammatory^ reaction, the healing of wounds, abnormal 

 growths, etc., are inevitably included. 



To return to the primary question of the genetic interpretation 

 of the endocrine organs: It was to be expected that the 'duct- 

 less glands' had been looked at by others from the point of 

 view here developed. Dohrn in 1875 formulated the follow- 

 ing "Principle of change of function:" 



