56 NATURE AND OBJECTS OF PHYSIOLOGICAL SCIENCE. 



there is any disorder in the heart's action, resulting from thickened 

 valves, narrowed orifices, &c., the physical influence of mental emotion 

 can be easily accounted for. But it must be admitted that cases have 

 occurred ? in which no such explanation can be offered ; sudden death 

 having taken place without any perceptible structural cause. We are 

 not obliged, however, to have recourse to any hypothesis, for an explana- 

 tion of even these cases, which is not borne out by ample analogy. For 

 it is well known that mental emotions, acting through the nervous force, 

 exert a powerful influence over the composition of the fluids of the body, 

 and are capable of instantaneously altering these. Thus in many human 

 beings, and still more in the lower animals, alarm or agitation will 

 occasion the immediate disengagement of powerfully odorous secretions, 

 which must have resulted from new combinations suddenly formed ; and 

 a fit of passion may immediately occasion such a change in the milk of 

 a nurse, as renders it a rank poison to the infant. There is no reason 

 to doubt, therefore, that the blood itself may undergo changes of analo- 

 gous character from the same cause ; and that it may become a violent 

 poison to the individual himself, instead of being the source of whole- 

 some nutriment, or the stimulus to vital activity. But the effect of 

 Electricity, of mental Emotion, or even of Mechanical force, may be 

 exerted more dynamically than organically ; destroying the vital powers, 

 by antagonizing the forces that produce them, without occasioning any 

 perceptible material change. This, in fact, we see in the state of pros- 

 tration or c shock,' induced by sudden and violent impressions of almost 

 any description. 



5. General Summary. 



70. To conclude, then ; we only know of lafe, as exhibited by an 

 Organized structure, when subjected to the operation of certain forces 

 which call it into activity ; and we only know of Vitality, or the state 

 or endowment of the being which exhibits that action, as conjoined with 

 that particular aggregation and composition which we term Organiza- 

 tion. We have seen that the act of Organization, and the consequent 

 development of peculiar properties in the tissues which are produced by 

 it, can only be attributed to the vital force of a pre-existing organism ; 

 and hence it is, that whilst the operation of Physical forces upon an 

 organized body gives rise to vital phenomena, no such phenomena can 

 be manifested as the result of their action upon any kind of inorganic 

 matter. It is in fact, the speciality of the material instrument thus fur- 

 nishing the medium of the change in their modus operandi, which es- 

 tablishes, and must ever maintain, a well-marked boundary-line between 

 the Physical and the Vital forces. According to the views here pro- 

 pounded, the Vital force is as different from Heat or Electricity, as they 

 are from each other ; but just as Heat, acting under certain peculiar 

 conditions, is capable of transformation into Electricity, whilst Electri- 

 city is capable, under certain other conditions, of being metamorphosed 

 into Heat, so may either of these forces, acting under conditions which 

 an Organized fabric alone can supply, be converted into Vital force, 

 whilst, in their turn, they may be generated by Vital Force. 



