INTERNAL SECRETION 503 



This secretion diminishes temporarily the normal toleration or assimilation 

 of sugar and in some unknown way leads to a hyperglycemia and glycosuria. 1 

 If the customary amount of sugar is ingested a portion of it will be eliminated 

 in the urine. 



If the posterior lobe with its epithelial investment is totally removed 

 or if the infundibular stalk is compressed by a clip so as to prevent the dis- 

 charge of the secretion into the ventricle the animal becomes very tolerant of 

 sugar and is enabled to assimilate larger quantities than formerly without 

 the development of alimentary glycosuria. As a probable result of the in- 

 creased carbohydrate assimilation, a condition of nutrition is established, 

 characterized by a general deposition of fat suggesting a conversion of the 

 sugar into fat. There is probably at the same time an imperfect oxidation 

 of the carbohydrates as indicated by the lowered temperature. 



That the condition of generalized adiposity is probably due to deficient 

 posterior lobe secretion is shown by the fact that the increased tolerance for 

 sugar can be lowered very promptly by the coincident intravenous or sub- 

 cutaneous injection of extracts of the posterior lobe. 



From the foregoing facts it may be assumed that the secretion of the 

 posterior lobe in some unknown way influences the metabolism of sugar. 

 From the facts at hand it may be assumed that a hypersecretion from any 

 cause whatever, leads to a diminished tolerance for or assimilation of sugar, 

 as shown by the hyperglycemia and glycosuria, though the manner in which 

 the hyperglycemia is developed, whether by a more rapid conversion of 

 glycogen to sugar or by an inefficient storage of sugar as glycogen is unknown. 

 A hyposecretion from any cause leads to an increased tolerance for or 

 assimilation of sugar which eventually contributes to the formation and 

 deposition of fat. In the complexus of symptoms that accompany patho- 

 logic changes in the hypophysis either in the anterior or posterior lobe it is 

 difficult to indicate those which are to be attributed to increased or decreased 

 secretion of either the anterior or posterior lobe by reason of their close 

 juxtaposition and their possible simultaneous involvement; again it is also 

 uncertain as to whether the secretions produce their effects alone or through 

 the cooperation of the secretions of other organs having more or less influ- 

 ence in the metabolism of the carbohydrates. 



The Effects of Injections of Extracts. The extracts of the anterior 

 lobe when intravenously injected appear to be without any appreciable effect 

 on any of the physiologic mechanisms. Injections of the extracts of the 

 posterior lobe, however, give rise very promptly, as shown by Howell, to an 

 increase in the blood-pressure which appears to be due to an increased 

 contraction of the arteriole muscle rather than to a stimulation of the vaso- 

 motor centers, as the contraction takes place even after destruction of the 

 spinal cord and medulla oblongata. The action of the active constituent 

 of the extract appears to be very general as there is a simultaneous diminution, 

 as shown by plethysmographic investigations, in the volume of various 

 organs. On the heart the extract has an inhibitor action which takes place 

 concomitantly with the contraction of the arterioles and the rise of the 

 pressure as shown by Howell. This is attributed to a direct stimulation of 



1 The normal tolerance for cane-sugar in the case of the dog, when it is given by the mouth is 

 about 10 grams per kilo of body-weight and for human beings about 2 grams (glucose) per kilo 

 of body-weight or approximately 150 grams. Any increase beyond this amount appears in the 

 urine indicating that the assimilation limit has been exceeded. 



