OPENING ADDEESS. 13 



electrical organ, the electrical effects were, in the single 

 instance which I have examined, extremely small, far 

 smaller than those which normally accompany the activity 

 of even the sartorius muscle of the frog, and that on the 

 other hand, this transitional structure, whilst it had no 

 electrical function to speak of, had in this particular case 

 no contracting function that could be detected by our 

 present methods. 



If this is so, it is obviously an unsound inference to 

 assume that this structure is one in which the function of 

 the two forms, those of muscle and electrical organ, are 

 represented ; they both appear to be non-existent. 



Here then alteration of structure has enormously 

 modified the function, but apparently in such a way as to 

 abolish its former predominant characteristic without 

 introducing that new characteristic which the newly 

 developing form would lead one to infer as being present. 



I bring forward this instance because of the essential 

 importance to any inquiry as to the structural changes in 

 living tissues due to their growth, of simultaneous 

 investigation into the alteration of the functional activity. 

 Comparative physiology of this kind would thus be of the 

 very greatest value for the correct interpretation of the 

 phenomena of growth and for the determination of the 

 question, as to how far it is the change in structure which 

 prescribes the change in function. Perhaps the change 

 in function may be the exciting cause for the alteration in 

 structure, for the force which we term " vital " sways the 

 mechanism which is after all nothing but it's tool. 



Third class of instances; inferring excitatory 

 Functions from Structures. 



If structure is not a sure guide to function even when 

 this function is definite and comparatively simple, it must 



