368 SEA-SIDE STUDIES. 



Mr Gosse's explanation will equally hold good if the bird's 

 head be a parasite, as I incline to think it is"; for not only is 

 it often absent from the very species on which it is com- 

 monly found, but it has independent action : last year I 

 separated one from the stem on which it was fixed, never- 

 theless the snapping continued as long as I was enabled to 

 watch it. One is naturally reminded of the analogous Pedi- 

 cellaria of the Star-fish. 



Whatever may be the conclusion respecting these birds' 

 heads, the action of the bird being thus closely imitated 

 puts us on our guard against the tendency to attribute 

 psychological motives to the actions of animals. Indeed, 

 unless we have previously assured ourselves of identity, 

 or at least great similarity of structure, we shall always 

 be in error when concluding an identity of fimction. Thus 

 in the last Chapter we saw how improbable is the sup- 

 position that the lower animals feel pain, in spite of our 

 admission that all animals possess Sensibility. And every- 

 v/here the study of Comparative Anatomy teaches us, that 

 before we can truly understand the Physiology and Psy- 

 chology of animals, we must acquire the most minute 

 knowledge of their structure. Much has already been done 

 in this direction, but much more remains to do. There is 

 still work for thousands of laborious students ; and all 

 genuine work will aid the science in its progress. Only let 

 men observe with patient zeal, and forego the temptation to 

 say they have seen what they have not seen, but what, from 

 the report of others, they expected to see (a temptation 

 which leads to the continuance of error more than any other 



