THE CAUSE OF INFECTIOUS DISEASE. 239 



internal cause as has been expended in its 

 construction. The manner in which the atoms 

 are grouped or bound together produces also 

 a definite resistance which may be overcome 

 with more or less difficulty. 



In these cases, therefore, the resistance bears 

 a much closer relation to the store of potential 

 energy than in most cases in inorganic nature ; 

 the resistance is a direct consequence of the pro- 

 cess of construction, and therefore a property 

 of the molecular structure. In the structure 

 and constitution of every organic body the total 

 amount of energy which may manifest itself 

 as effect exists as the potential energy of com- 

 bination, as the internal cause. The kind of 

 energy is prefigured also in the molecular 

 structure, and so, finally, is the kind and 

 amount of resistance which prevents the im- 

 mediate and free transformation of cause into 

 effect. I have explained the reasons for the lat- 

 ter phenomenon briefly, as it is unnecessary to 

 consider details in this place. The looser and 

 more manifold the atom-grouping of a mole- 

 cule is, the more energy the molecule con- 

 tains ; so much the less also is the energy 

 needed to overcome the resistance and liberate 

 the energy of the molecule, and so many more 

 are the different kinds of external impulses 

 which are able, by the application of aniso- 



