INTERNAL SECRETIONS 523 



causes a rise of blood-pressure, accompanied by marked diuresis. 

 A second injection generally does not affect the arterial pressure^ 

 but the diuretic action is still marked in fact, the active substance 

 may be regarded as the most potent diuretic known. The smooth 

 muscle of the pupil and uterus is also affected by pituitary extract, 

 and it is used by clinicians to promote contractions of the uterus. 



The contractions of the bladder are also increased in the dog and 

 rabbit by the injection of pituitary extract. The excitability of the 

 pelvic nerve supplying this viscus is increased, while that of the 



FIG. 261. A CASE OF ACEOMEGALY. (Photograph kindly lent by Dr. T. Reuell 



Atkinson.) 



The head measurements are Circumference, 25 inches; from forehead to chin, 

 11 inches; from nape of neck to chin, over nose, 25 inches. The lower jaw pro- 

 trudes 1J inches in front of the upper. The two hands measure 6 inches across 

 the root of the thumb and 5 inches across the root of the fingers. When closed 

 the hand measures 15 J inches round. 



hypogastric nerves is unaltered. Pituitary extract ha* no action 

 upon other organs supplied by the autonomic system, such as the 

 heat t and the salivary glands ; an action upon the intestine is doubtful 

 The extract of the infundibulum is also a powerful galactagogue, 

 and the active substance can be obtained from both the intermediary 

 and posterior lobes (Fig. 260). The active substance is probably 

 derived from both lobes, but chiefly from the intermediary lobes. Its 

 exact nature is unknown, but its action is closely allied to bodies of 

 the digitalis series, and it apparently acts directty upon muscle rather 

 than upon the nerve or nervous connections. 



