TUBULARIA. 37 



IV. — On expulsion of the ovum from the cyst a hydra is unfolded, 

 which enjoys the faculty of locomotion, and in its earlier stages evinces 

 animal nature exclusively. 



V. — After a brief display of the locomotive faculty, the hydra becomes 

 rooted permanently, and thus it flourishes, enlarges, multiplies, and dies. 



VI. — ^The original hydra reared on the first elongated stem falls from 

 its summit, after a certain but indefinite interval from its evolution, and 

 perishes below. 



VII. — One or more hydrse, according to the vigour of the specimen, 

 replace in succession that which has first fallen. 



VIII. — If the luxuriance of the hydra be great when the subject is 

 originally recovered from the sea, that of its successor is generally inferior. 



IX. — No correspondence appears between the dimensions and the 

 number of regenerated organs of the successor, and those of its immediate 

 precursor. 



X. — No uniform length of interval prevails between the regeneration 

 of the successive hydrae, some being evolved much more speedily than 

 others. 



XI. — No uniform duration prevails among the regenerated hydrae. 



XII. — Prolongation of the stem is absolutely dependent on the exist- 

 ence of the hydra, and the rate of increment generally corresponds to its 

 duration. 



XIII. — Six successive hydra may be generated from the summit of 

 the same stem in six months. 



XIV. — ^The germ or elements of each hydra probably reside at some 

 distance from the summit of the stem. 



XV. — A greater number of hydrae than apparently allotted by nature 

 to a single stem, may be obtained by artificial sections or subdivisions of it. 



XVI. — By such subdivisions, 22 hydrae have been generated in 550 

 days from three sections of a single stem. 



XVII. — Monstrosities from external injury to succeeding hydrae be- 

 fore evolution are gradually effaced in each successor ; and symmetry, to 

 which there appears a constant tendency, is restored, in remote regenera- 

 tions. 



