20 GENERAL PART 



the heat regulation occur most commonly and most pronouncedly in diseases 

 of the thyroid gland. In myxedema the bodily warmth often sinks far below 

 the normal; in Basedow's disease hyperthermia is not rare. In the one the 

 vegetative functions are diminished, in the other increased; the diminished or 

 increased heat production cannot, however, alone be the cause. There must 

 occur in addition other sorts of disturbances, especially in the mode of action 

 of the vessels of the skin or in the vegetative nervous system, changes that 

 I shall not go into here on account of their complexity. On the ground last 

 mentioned, it is well also to ascribe to the chromaffin tissue an important 

 role in the regulation of heat, for adrenalin, as may readily be demonstrated 

 experimentally, through contraction of the vessels of the skin and prevention 

 of the perspiration may lead transitorily to a significant hyperthermia, even 

 with shivering. Also the hypophysis seems to enter into the regulation of 

 temperature on account of its influencing the vegetative nervous system ; to 

 this statement points the fact that in hypophysial dystrophy the temperature 

 always is instituted at an abnormally low level. I content myself with these 

 few examples; the intimate relation of the ductless glands to the vegetative 

 nervous system, which I shall speak about later, furnishes obvious explana- 

 tion. The same holds true for the influencing of the water economy; retention 

 of water in myxedema, with throwing off of water in this condition by the use 

 of thyroidin, polyuria in the "hypertonic diathesis/' diabetes insipidus in 

 individuals with disease of the hypophysis, diabetes decipiens or high-grade 

 polyuria in diabetes mellitus, are all questions which have as yet been very 

 little investigated and the study of which represents many results. 



Embryology of the Ductless Glandular System 



Before I attempt to group the blood-glands according to their functions, I 

 should like to say a few words as to the embryology of the ductless glandular 

 system. It is a shame that this subject has to the present been somewhat 

 neglected by the embryologists. All three germinal layers contribute to the 

 structure of the ductless glandular system. According to the contributions 

 that I have found in the literature, it seems to me that the following grouping 

 is possible: 



The chromaffin tissue is of neuroectodermal origin. 



The posterior lobe of the hypophysis is also of neuroectodermal origin. 

 The pars intermedia is also of ectodermal origin. It is questionable, 

 however, whether the pars intermedia develops from the anterior or 

 the posterior lobe. In the latter case it would be of neuroectodermal 

 origin. 



The anterior lobe of the hypophysis develops from an extrusion of the 

 dorsal wall of the ectodermal primary mouth cavity where it passes 

 over into the entodermal head-gut. 



