THE DUCTLESS GLANDS. 405 



splanchnic area have already been described (p. 234). Anaesthetics, 

 such as chloroform, also excite the centre and bring about a discharge 

 of adrenalin. 



In all probability, the varying activity of the suprarenal glands, 

 brought about by impulses reaching them along the splanchnic nerves, 

 plays an important part in the adjustment of the vascular system to 

 the changes constantly taking place in the body. A striking instance 

 of this adjustment is seen, as Cannon has pointed out, in states of 

 violent emotion, such as rage, pain, or fear. The additional adrenalin 

 sent into the blood stream in these circumstances increases the sugar 

 in the blood, thereby providing a further supply of sugar to the 

 skeletal muscles, and also improves the nutrition and efficiency of 

 the heart and the blood supply to the brain. In this way the reaction 

 of the animal to these emotional states, by movements of attack or 

 defence, is rendered more effective. 



Owing to its action on the blood-vessels, adrenalin has proved of 

 great value, both in checking haemorrhage when applied locally, and in 

 raising the arterial blood pressure in the condition of shock. In 

 Addison's disease the repeated injection of adrenalin is stated in some 

 cases to produce improvement, though the disease cannot be cured. 



THE PITUITARY BODY (HYPOPHYSIS CEREBRI). 



The pituitary body, which lies in the sella turcica and is connected 

 by the infundibulum with the third ventricle, is a small mass consisting 

 of two lobes, anterior and posterior. The posterior lobe originates as 

 an outgrowth from the under surface of the brain, and at first is hollow ; 

 in man the cavity ultimately disappears and it is composed entirely of 

 neuroglia. The anterior lobe arises as a hollow projection from the 

 buccal epithelium, and in the adult consists of a solid mass of cells, 

 many of which are clear -and stain deeply with eosin, whereas others 

 are very granular. Between the columns of cells are numerous 

 capillaries. 



The two lobes are separated by a narrow cleft lined by clear cellt^, 

 which form the pars intermedia and are most abundant on the posterior 

 wall of the cleft, partially surrounding and extending into the posterior 

 lobe. The cells tend to become transformed into colloid material, 

 which ultimately reaches the cavity of the third ventricle. 



Complete removal of the whole gland or of the anterior lobe is 

 followed by death in a few days, though the animals survive when 

 minute fragments of the anterior lobe are left. After partial removal 

 of the anterior lobe, young animals often show abnormal metabolic 



