160 THE DISEASES AND DISORDERS OF THE OX. 



for the fight or for the escape from an enemy. He says that in 

 uraemic coma the pupils are generally contracted so long as the 

 patient is free from convulsive movements, hut that as soon as a 

 convulsion comes on the pupils dilate. When the convulsion 

 ceases the pupils again contract. Similarly, he says, the pupils 

 dilate in the convulsions of epilepsy. He has noticed also that 

 when a patient is returning to consciousness after chloroform 

 narcosis the contracted pupil gradually dilates ; but that if the 

 patient move about the pupil will at once dilate largely, and on 

 the subsidence of the movement again become smaller. He 

 connects all these facts, drawn from so-called abnormal states, 

 with an association (brought about by the struggle for exis- 

 tence) between alertness for action and increase of field of view 

 caused by dilatation of the pupil, an association which he says 

 is due to an inhibition of the nerves of vaso-motor areas in 

 muscles and to a correlated stimulation of the sympathetic 

 nerve which innervates the radiating muscle of the iris of the eye. 



The endocarditis of chronic Brights' Disease is attributed to 

 the extra blood-pressure, which indeed is one of the earliest 

 manifestations of inflammation of the kidney. Hence the value 

 of the subjugation of pain in cases of endocarditis and of peri- 

 carditis of rheumatic fever may be to some extent due to the 

 coincident soothing of the heart. 



We see, then, that the occurrence of pain, due to whatso- 

 ever cause, arouses the associates of work, not only in health 

 but also in disease, though, of course, we must not forget that 

 the sufi'erer may become exhausted, and therefore no longer 

 able to manifest the processes referred to. Now the constitu- 

 tional unrest which is set up by the pain consequent upon 

 injury must, and does, work harm. 



For the sake of example, suppose we consider, for a moment, 

 the case of an animal which has just gained the victory over 

 an opponent, and let us further suppose that the ultimate van- 

 quishing of the foe was the result of the redoubled efforts which 

 were made owing to the reception of an injury which stimulated, 

 or rather evoked, the closing energetic and successful struggles. 



In connection with this most important question of pain in 

 its relation to vital activities, Dr. D. A. Gresswell would add 

 that not pain alone, but the mere apprehension of pain due to 

 any want of well-directed and sustained effort — which would 



