SECRETION. 463 



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 gtycogen 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 

 the cardio-inhibitor center as the retardation is partly prevented at least 

 when the vagus is divided or its function suspended by atropin. Even after 

 this has been done, however, a slowing of the heart may still be induced, a 

 fact which suggests that the extract acts directly on the heart muscle as well. 

 Schafer and his co-workers have also demonstrated that pituitary extracts 

 cause dilatation of the renal vessels and stimulate specifically the renal cells 

 to activity, thus causing a marked diuresis. The extract also stimulates the 

 non-striated muscles of the intestines, bladder, uterus, as well as the dilatator 

 muscle of the iris. 



Adrenal Glands, or Suprarenal Capsules. These are two flattened 

 bodies, somewhat crescentic or triangular in shape, situated each upon the 

 upper extremity of the corresponding kidney, and held in place by connective 

 tissue. They measure about 40 mm. in height, 30 mm. in breadth, and 

 from 6 to 8 mm. in thickness. The weight of each is about 4 gm. Acces- 

 sory glands are sometimes found in the surrounding connective tissue along 

 the abdominal sympathetic and in the neighborhood of the genital organs. 



In some animals such as the dog, cat and rabbit, these glands have no 



