76 POPULAR ILLUSTRATIONS OP 



instance, although there is no doubt that legs and arms have actually 

 been seized by these creatures. 



We shall best study the Hydra by looking at what we may term 

 its morphology, or the different forms which it assumes in what are 

 called Zoophytes, or plant-like animals. The word zoophyte is now 

 limited to that class of animals of which the Hydra is the type, 

 termed Polypifera, the compound skeletons of which have a plant- 

 like form. The term coralline, often popularly applied to this 

 group, is restricted to a small class which the botanists lay claim to, 

 and which are at once distinguished from the Zoophytes by the 

 absence of all traces of cells on their surface a fact which the sea- 

 side rambler, armed with a pocket lens, will verify for himself at 

 any time. 



Suppose, then, the said rambler finds, between tide marks attached 

 to a sea- weed, a form like the small central figure (97, p. 74), he will 

 at once by the above test know that he has a Zoophyte ; and if he 

 place it in a small glass of sea-water, and watch it with a lens, he 

 will observe at the end of each tube a fleshy-looking body, which 

 gradually protrudes its tentacles. This is -one of the Oorynidse, or 

 club-shaped Zoophytes. It is the simplest form which the hydra- 

 form animal assumes among the covered species. The tentacles, it 

 will be observed, spring from all parts of the polyp's body, and 

 although they can be drawn in and extended at pleasure, the body 

 cannot be withdrawn into the tube. The tentacles are very short, 

 and some of them being at a considerable distance from the creature's 

 mouth, the latter bends its purposely provided mobile neck and 

 meets the food which these distal tentacles may get hold of half way. 



That part of the tube which is attached to the stone or sea-weed 

 is termed the root, and in this genus is closed. The branching 

 tubes, however, are all hollow, and are filled with a continuation of 

 the same substance as that which constitutes the body of the polyp 

 (Figs. 98, 99, p. 74), thus forming a compound animal, it may be, of 

 a hundred or a thousand brilliantly-coloured scarlet, or red, or rose 

 polyps, all connected with each other, and yet to a certain extent 

 independent organisms. 



The reader will be somewhat reminded of the Ehizopoda before 

 described and figured ; but he will remember tnat when the 

 Lieberkuhnia, or Gromia, caught any prey in their pseudopodia it 

 was digested there and then, and the nutriment was conveyed into 

 the general, though imperfect and irregular, circulation. In the 

 Hydra and its congeners, however, the prey is brought by the ten- 

 tacles to the mouth, and is swallowed and digested in a regularly 

 formed stomach. Hence the great biological difference between the 

 two forms. The animal inhabiting the Corynid as well as the other 



