122 THE OCEAN WORLD. 



pieces into which it has been divided." "The same polyp," says 

 Trembley, " may be successively inverted, cut in sections, and turned 

 back again, without being seriously injured." 



If a green Hydra is cut into two pieces, and the stomach is 

 cut off in the operation, the voracious creature will, nevertheless, 

 continue to eat the prey which presents itself. It gorges itself with 

 the food, without troubling itself with the loss which it has sustained ; 

 but the food no longer nourishes it, for it merely enters by one 

 opening, passes through the intestinal canal, and escapes by the 

 other. It realises Harleville's pleasantry of M. de Crac's horse, in 

 the piece of that name, which eats unceasingly, but never gets any 

 fatter. 



All these instances of mutilation, resulting in an increase of life, are 

 very strange. The naturalists to whom they were first revealed could 

 scarcely believe their own eyes. Reaumur, who repeated many of 

 Trembley's experiments, writes as follows : " I confess that when I saw 

 for the first time two polyps forming by little and little from that 

 which I had cut in two, I could scarcely believe my eyes ; and it is a 

 fact that, after hundreds of experiments, I never could quite reconcile 

 myself to the sight." 



In short, we know nothing analogous to it in the animal kingdom. 

 About the same period Charles Bennet writes : " We can only judge 

 of things by comparison, and have taken our ideas of animal life from 

 the larger animals ; and an animal which we cut and turn inside out, 

 which we cut again, and it still bears itself well, gives one a singular 

 shock. How many facts are ignored, which will come one day to 

 derange our ideas of subjects which we think we understand ! At 

 present we just know enough to be aware that we should be surprised 

 at nothing." 



Notwithstanding the philosophic serenity which Bennet recom- 

 mends, the fact of new individuals resulting from dividing these 

 fresh-water polyps was always a subject of profound astonishment, 

 and of never-ending meditation. 



CORYNID^E. 



We have already said that recent researches have led to a separa- 

 tion of this class of animals from the Sertularidse, and to their being 

 formed into an order by themselves. Of these creatures we formerly 

 only knew one of the forms, namely, the polyp form ; or, rather, the 

 first stage of it. During their earliest days they possess a polyp, fur- 

 nished with tentacles, and a bell-shaped body. During their medusoid 



