262 VETERINARY HOMCEOPATHY. 



be proved by dividing the cord, when the parts that receive their 

 nerve supply from the portion below or posterior to the division 

 are paralyzed both as to feeling and the power to move, for the 

 connection with the nerve centre which may either be located in 

 the brain or in a part of the cord above the division is severed and 

 the ''path of conduction " is broken up; the same result transpires 

 when through an injury the spinal cord is ruptured, as does occur 

 sometimes to horses in the hunting field or while running in a 

 steeplechase; the common method of testing the seat of injury to 

 the spine is to prick the body and legs with a sharp pin; if the 

 animal displays no sense of feeling in certain parts while it evinces 

 pain in others, it is comparatively easy to determine approximately 

 the seat of injury, as well as to come to an authoritative diagnosis 

 with relation to its extent and serious consequences. Reference 

 has already been made to the inhibito>y or restraining action of 

 some nerves and an illustration furnished; another instance may 

 be mentioned of a similar kind of action, which has an interesting 

 bearing upon the consideration of certain difficulties that beset the 

 horse when called upon for a supreme effort of speed, namely, the 

 power of restraining the beating of the heart which is effected 

 when certain fibres of the pneumo-gastric nerve are unduly stim- 

 ulated; now, it must be explained that the pneumo-gastric nerve 

 is endowed v^ith very complex functions; its centre is in the brain, 

 and there it is very intimately associated with two other of the 

 cranial nerves; among other functions, it presides over the pro- 

 cesses of digestion in the stomach and intestines, which it serves 

 to stimulate; but the branch that goes to the heart exercises the 

 exactly opposite (the inhibitory) function, and according to the 

 extent this branch is stimulated, it may either act usefully in pre- 

 venting the heart from beating too frequently, or it may act 

 prejudicially by arresting its action altogether; the point therefore 

 which is of interest to the practical horseman is, that whereas the 

 pneumo-gastric nerve is endowed with the power of producing two 

 exactly opposite kinds of impulse, one branch going to and acting 

 upon the digestive organs, while the other goes to the heart, an ex- 

 planation is furnished of how some animals under peculiar circum- 

 stances are easily affected by careless feeding, or by calling upon 

 them to perform work that demands special fitness at times when 

 they are totally unfit to make anything like a violent effort. 



