1086 PHYSIOLOGY 



coronary arteries are diseased or calcified. In such cases a man may 

 drop down dead, having previously shown no symptoms of heart 

 mischief. 



Delirium cordis may be explained as the result of block, produced 

 by interference with the nutrition of a large part of the heart- wall. 

 The contractile wave arriving at this part, in some directions will not 

 spread at all, in others will spread at a lower rate, so that different 

 parts of the heart receive the impulse to contract at different times 

 and a state of inco-ordination results. The same condition can be 

 produced by freezing the apex of the ventricle, so causing a block, 

 or by stimulating the surface of the ventricle at a rate which is greater 

 than can be taken up by the ventricle as a whole, as, e.g., by tetanising 

 currents. Such a condition in the higher animals, as the dog and man, 

 is practically irrecoverable, although in the rabbit, and very rarely 

 in the dog, it is sometimes possible to bring the heart back to a state 

 of rhythmic contraction by kneading it rhythmically. 



