240 HUMAN PHYSIOLOGY 



place reflexly by stimulation of the conjunctival nerves, 

 by strong light, and by psychical influences (weeping). 



5. In the medulla oblongata is situated a spot which is 

 connected with the glycogen and sugar formation in the liver 

 (see page 146). Destruction of this centre (Piqure) causes 

 diabetes mellitus. 



6. It is supposed that there exists in the medulla oblon- 

 gata a centre which governs the reflex centres in the spinal 

 cord and binds these centres together. It is supposed to 

 be stimulated by lack of oxygen and accumulation of carbon 

 dioxide in the blood, w r hereby convulsion of all the muscles 

 in the body (asphyxia convulsion) is produced. Hence this 

 centre is also called the centre of convulsion. 



3. CENTRES IN THE CEREBELLUM, PONS, CORPORA 

 QUADRIGEMINA, AND THE BASAL GANGLIA* OF 

 THE CEREBRAL HEMISPHERES 



The centres here located serve, as far as we are acquainted 

 with their functions, to coordinate the movements of the 

 skeletal and eye muscles. They may be divided into two 

 groups. 



i . Centres for the coordinated compensatory movements 

 maintaining the equilibrium of the body. These centres 

 bring about a series of complicated orderly movements of 

 the muscles so that the body keeps its equilibrium. When, 

 for example, during standing or walking the equilibrium of 

 the body is destroyed so that the body threatens to fall, the 

 centres call forth such compensatory movements of the body 

 muscles that the equilibrium and the normal position are 

 regained. When the disturbance of the equilibrium is great, 

 these actions can be readily observed, but these compensa- 

 tory movements also take place when the position of the 

 body deviates but little from the normal position. In this 

 case the movements are less apparent and made so uncon- 

 sciously that our attention is called to them only in certain 



* The basal ganglia are the thalamus opticus, nucleus caudatus, and the 

 nucleus lenticularis. 



