212 STUDIES IN LIFE AND SENSE. 



tific terminology, perhaps, than for the reader's feelings, we shall 

 name the " pneumogastric " or " vagus " nerve. This latter nerve 

 originates from the upper portion of the spinal cord, esteemed, and 

 justly so, as the most sensitive and important of the brain centres. 

 So much for an elementary lesson in the nervous supply of the 

 heart ; the outcome of such a study being, that the heart much re- 

 sembles a conjoint railway station, in which three companies possess 

 an interest, and whose lines enter the structure. The chief pro- 

 prietors of the station are represented by the small sympathetic 

 nerves and nerve-centres, which belong to the heart's own sub- 

 stance, whilst the fibres of the sympathetic nerve, and those of 

 the pneumogastric nerve, represent the other lines that traverse 

 the common territory, and affect the traffic carried on within its 

 bounds. 



Now, in the relations borne by these various nerves to the work 

 and functions of the heart, we may find a very typical example of the 

 dominance occasionally assumed by the mind over a function of the 

 body which, under ordinary circumstances, is carried on without the 

 control of the head-centre of the frame just, indeed, as the head 

 of a department may sometimes interfere with the placid way of life by 

 means of which his efficient subordinates may discharge the duties 

 they owe to the country at large. For, what has experimental physi- 

 ology to say regarding the explanation of the effects of joy or sorrow, 

 fear and anguish, and the general play of the passions on the heart ? 

 Under the influence of the emotions, the organ of the circulation is 

 literally swayed beneath varying stimulation, just as in metaphor we 

 describe it as responding to the conflicting thoughts, which, whilst 

 they primarily affect the brain, yet in a secondary fashion rule the 

 heart and other parts of the body. The trains of thought in fact 

 despatch to the heart, along either or both of the nerve-lines already 

 mentioned, portions of their influence, with varying and different 

 effects. Take for instance the effects of fear upon the heart-throbs. 

 Who has not experienced the stilling of the heart's action which a 

 sudden shock induces? or that chilling sensation, accompanied by the 

 sudden slowing of the pulses, which every poet has depicted as the 

 first and most typical sign of the startled mind ? Such a familiar 

 result of strong emotion illustrates the effect of mind upon body in a 

 fashion of all others most clear and intelligible. Here an ''inhibitory" 

 action has taken place, through the medium of the " pneumogastric n 

 nerves. By irritating or stimulating these nerves, we may slow the 

 heart's action, or may cause that action to cease. It is from some 

 such source also, that the influence of fear, or of that emotion which 

 holds us rapt " with bated breath," or which keeps us " breathless 

 with adoration," proceeds. Like the action of the heart, the process 

 of breathing responds to the will and sway of that mental counsellor 



