6 TBANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



to the external stimulus I apply to it, but to the more 

 subtle and unknown stimulus which emerging from the 

 central nervous system courses down to it along its nerves. 

 The form is certainly there, but not necessarily the function. 

 Many of the muscles of our body will contract to a stimu- 

 lus and are supplied by nerves which reach them from 

 the central nervous system, but we cannot by the strongest 

 voluntary effort make them act. Indeed, even those 

 muscles which do so contract in response to the will act 

 but in a partial and incomplete manner, and more exact 

 inquiry seems to show, that although all the component 

 muscular fibres are structurally alike, they do not all 

 respond alike to the will stimulus — some remaining 

 quiescent. It would therefore be a much bolder assumption 

 to infer from the structure of a muscle the functional 

 characters of its activity in the living animal. Experi- 

 mental investigation alone can decide these. 



Yet undoubtedly, on the discovery in an animal of a 

 mass of muscle, there is irresistibly forced on the mind 

 the conviction that since its structure and connections 

 resemble those of other muscles, its functional activities 

 must do so too. We jump from ascertained structure to 

 unascertained function, and why? Because a vast number 

 of instances of an accurate correlation of structure and 

 function force the judgment to this leap. What has been 

 so often must be again, and in the majority of cases will 

 be so again. There is thus a very great probability that 

 this jump is one on to sure ground, but it may be a 

 plunge into the abyss. This is the rock on which many 

 a purely structural investigator has suffered shipwreck. 

 A conviction has been forced upon his judgment such as 

 Wordsworth expressed in his Duddon sonnet. " The 

 Form remains the Function never dies." 



Let us be perfectly clear that structure does not deter- 



