110 PARTICULAR FRACTURES. 



fluttering, and perhaps intermittent ; the pupils are dilated if 

 the concussion be very severe, but tliey will usually contract on 

 the application of a light, showing that the retina is not per- 

 fectly insensible. If the concussion be slight, the pupils will 

 be found contracted, or poss'bly one pupil may be contracted 

 and the other dilated. These symptoms may change into the 

 second stage, or into those of compression, or they may ter- 

 minate fatally without any other change. 



Second Stage. — The insensibility is diminished, sensation and 

 volition are partly restored, but ordinary impressions produce 

 little effect, and the animal lies in a kind of sleep, although it 

 is possible to rouse him for a moment by speaking loudly 

 or harshly ; pricking by a pin causes him to show feeble 

 signs of pain ; there are occasional signs of restlessness ; the 

 pulse and circulation are more vigorous ; the skin and the 

 extremities become warm by degrees ; and the animal will now 

 and then make efforts to rise, which always produces an 

 accelerated condition of the pulse, with loud beating of the 

 heart. These 8}'mptoms may subside, or may pass on to the 

 third stage, namely, that of pure inflammation of the brain, with 

 throbbing of the carotids and vessels of the head, injected con- 

 junctiva, suffusion of tears, intolerance of light and sound, 

 watchfulness, restlessness and delirium, with strong quick pulse, 

 lieat and dryness of the skin, diminution of the secretions, and 

 other symptoms of irritative fever. These sjrmptoms may yield 

 to treatment, which must be prompt to be effectual, or they 

 may pass on to those of compression, and prove fatal 



I>IFFERENT WAYS IN WHICH CONCUSSION PROVES FATAL. 



By careful experiments, the whole of the brain and spinal 

 cord have been removed, and so long as artificial respiration 

 was kept up, the action of the heart continued for some hours. 

 From these experiments it has been concluded that the action 

 of the heart is independent of the brain and spinal cord. But 

 it has also been discovered that when any sudden injury, such 

 as a violent concussion, is produced on a part of the brain or 

 spinal cord, an immediate and great depression, or complete 

 suspension, of the action of the heart is the result. From this 

 it is concluded that a sudden injury of the nervous centres. 



