REPRODUCTION OF HYDRA. 523 



several of these bearing another generation, as many as eighteen 

 have been observed united in one group. Sometimes the whole 

 process is concluded within twenty-four hours ; so that, at this 

 rate of production, above a million would be formed in a month 

 from a single Hydra. 



1172. It is not only in this manner, however, that the Hydra 

 propagates itself. The process just described is evidently analo- 

 gous to the extension by buds, which is so characteristic of 

 Plants. But there is another mode of reproduction in the 

 Vegetable kingdom that by seeds or spores ; and this, also, the 

 Hydra possesses, in common with all the higher tribes of Animals. 

 Towards autumn, some little gelatinous globules are seen to be 

 liberated from the tissue of the Polype. These fall to the bottom 

 of the water, and remain undeveloped until spring ; when they 

 produce a new generation of Hydra. 



1173. Perhaps the most remarkable feature in the history of 

 the Hydra, is its capability of reproducing the whole structure 

 from separate portions of it. Not only will the body send forth 

 new tentacula, to replace any which have been accidentally lost 

 or artificially removed, but the arm thus separated has the power 

 of developing the whole body. If the body is divided trans- 

 versely, each segment will become a new animal ; the upper one 

 closing the aperture at its base, and the lower one speedily 

 developing tentacula around the newly-fdrmed mouth. If divided 

 longitudinally, each half will form a separate tube in an hour, by 

 the folding-in of its edges, and will soon begin to ply its ten- 

 tacula. Even if divided into several longitudinal strips, each 

 becomes a new tube ; not as before, however, by the folding in 

 of its edges, but by the formation of a cavity in its substance. 

 If cut transversely into several segments, each will in time 

 become a perfect animal, so that thirty or forty Hydrce may thus 

 be produced by the section of one. Further, by slitting the 

 tube at one end only, two heads or two tails may be formed 

 each division soon becoming perfect in itself. These may be again 

 divided, and any amount of multiplication may thus be effected, 

 thus realising in Nature the Hydra of ancient fable. The animal 

 does not appear to suffer from these operations, for it is 



