74 SEA-SIDE STUDIES. 



Williams — in common with most, if not all, anatom- 

 ists — speaks of the muscular parietes of these ten- 

 tacles. I venture to suggest that there is great 

 inaccuracy in the term ; and that the existence of 

 these muscles is a pure assumption, assumed to explain 

 the Contractility of these organs, in the same way as a 

 nervous system is constantly assumed to explain some 

 phenomena of Sensibility, although not a trace of a 

 nerve can be detected by the highest powers of the 

 microscope. The assumption is in each case perfectly 

 needless, and very misleading. It is against all philo- 

 sophy thus to assume the existence of a tissue no one 

 can detect, to explain a phenomenon which may be 

 otherwise explained. Nor is anything gained by de- 

 clarinoj that the nervous tissue is in a " diffused state." 

 This is making an assumption, and conceaHng it in a 

 phrase. If I were to declare that gun cotton contained 

 nitre, because gunpowder contains it ; and if, when my 

 statement was answered by repeated analyses proving 

 no nitre to be there, I were to reply, " the nitre may 

 not be detected by your analysis, because it is in a 

 diffused state," you would shrug contempt at such 

 chemistry. But this is precisely analogous to what is 

 done daily with respect to nervous tissue. Men assume 

 that all animals must have nerves ; if the nerves are 

 not visible, it is because they are " diffused.'' Now, this 

 reasoning is not only vicious as logic, it is particularly 

 vicious in Biology, where structure is of equal import- 

 ance with composition. Nerve is a specific thing, 

 having a specific composition, and a specific structure ; 



