ORIGIN OF DISEASE AND THE GERM THEORY. 159 



may be possible. In short, nearly all the muscles of the body 

 are liable to be called into action. The wild and piercing cries 

 uttered by a creature almost worsted in the deadly strife, as 

 they re-echo far and wide, may avert a threatened defeat by 

 frightening the antagonist, perhaps, or at any rate by attracting 

 comrades to help. The excitement is associated with more 

 rapid circulation, with quickened action of the heart, with rise 

 of the external temperature, and of the body temperature as a 

 whole. 



Now in pain, also, the temperature often rises measurably, and 

 it falls when, as by the influence of morphine or otherwise, the 

 suflfering is subdued. In this relation it is well to bear in mind 

 that peripheral increase of heat may occur, though the oral tem- 

 perature be not altered. The augmented action of muscles and 

 organs gives rise to an increased amount of waste products, 

 and this in due course to sweating and loadening of the rectum 

 and bladder. A man or a horse suffering from the pain of 

 enteritis sweats profusely. There may be also, during pain, as 

 also during excitement, an additional sensibility to cold. 



Dilatation of the pupils takes place during pain. Dr. D. A. 

 Gresswell noticed that the pupils of a lad suffering from Peliosis 

 rheumatica dilated whenever one of the elbows, which was 

 exquisitely tender, was accidentally pressed. He has also 

 observed dilatation of the pupils in vigorous children under- 

 going tracheotomy, in cases when an anaesthetic could not be 

 administered. The pupil also frequently dilates in cases of 

 locomotor ataxy, when an attack of pain comes on. On the 

 other hand, during sleep, when the centres of sensation are 

 dulled, the pupil contracts, as also in opium stupor, in the 

 stupor of typhus fever, in that of typhoid fever, and also in that 

 of relapsing fever, also in the anaesthesia produced by chloro- 

 form, notwithstanding that in the stage of profound narcosis 

 which supervenes immediately before death they may dilate. 

 Some animals — for instance, the cat — when preparing for action 

 show dilatation of the pupil ; and also in human beings the 

 pupil dilates if sensory nerves be strongly irritated, or as a result 

 of excitement, or during severe muscular exertion. 



Dr. D. A. Gresswell ascribes this dilatation of the pupil 

 which occurs in an animal suffering pain to the necessity of 

 obtaining a wide field of view, whether in the alertness needed 



