162 SEA-SIDE STUDIES. 



The foregoing discussion has had a purpose beyond 

 that of rectifying an universal error — the purpose of 

 pointing a lesson in Comparative Anatomy. The 

 greatest living experimental physiologist, Claude Ber- 

 nard, has recently insisted with emphasis on the 

 importance of recognising " anatomical deduction " to 

 be a fruitful source of error.* He warns us against 

 attempting to deduce a function from mere inspection 

 of the organ, without seeing that organ in operation, 

 and applying to it the test of experiment. As a case of 

 pure deduction, this hypothesis of the " urticating cells" 

 seemed to command, and did command, instantaneous 

 assent ; but on submitting it to verification, we find the 

 hypothesis to be an error. To the philosophical mind, 

 therefore, there will have been an interest in the fore- 

 going discussion greater than any interest issuing out 

 of the mere conclusion respecting the thread-capsules. 



Amon^ other thinos, it will illustrate the need there 

 is for rigorous scepticism, and extended observation, on 

 the part of zoological students. So long as we unsus- 

 pectingly accept what is repeated in books, without 

 being assured that the statements are made on suf- 

 ficient evidence, and so long as we have eyes but 

 observe not, zoological progress will necessarily be slow, 

 in spite of the vast number of excellent observers and 

 workers, who do accelerate our progress by genuine 

 work. When I insist on the necessity for circumspect 

 doubt, and verified observation, the reader must not 

 understand me as implying that this necessity is not 



* Legons de Physiologie Ex2oerimentale,Yo\. ii. : 1856. 



