WHAT IS DIGESTION? 207 



cious, with anatomical deduction, declaring an organ to have 

 sucli and such a function, merely because it resembles an 

 organ known to have the function ; when in most of these 

 cases, direct experiment would show the error of the conclu- 

 sion. In former chapters I have illustrated this pomt, and 

 have again to do so respecting the digestive power of the 

 Sea Anemones. 



In my note-book is pencilled this brief query, " Do the 

 Actinife digest at all ? " a doubt which, in its naked simpli- 

 city, might rouse contempt in the mind of any zoologist 

 accidentally reading it. What ! here is an animal notoriously 

 carnivorous, and you ask whether it can digest ? Have not 

 you yourself repeatedly fed these animals with limpets and 

 cooked beef? are they not greedy of such food? It is per- 

 fectly true. Nevertheless a doubt occurred to me whether 

 they did really digest, in any proper sense of the term ; and 

 I made a note of the doubt, as of a point to be investigated 

 immediately on my arrival at the coast. Experiment should 

 settle the doubt. Before narrating the experiments, it will 

 be needful to settle with the reader a few generalities on the 

 subject of Digestion ; since, in point of fact, the interest of 

 the question falls mainly on the general subject, and only 

 with a secondary importance on the digestive powers of the 

 Anemones. 



What are we to understand by Digestion ? At first the 

 question seems so easy ; yet the closer it is investigated, the 

 remoter seems the possibility of answering it. Let us make 

 a clearance by first discriminating Digestion — as a special 



