TUBULARIA. 55 



when withdrawn from the sea, only 40 subsisted on the second day ; 30 

 on the third ; 12 on the sixth ; 4 on the seventh ; 2 on the eighth ; on the 

 tenth there were none : the whole had fallen. This was a beautiful speci- 

 men. It might have been circumscribed by a circle the size of a shilling. 

 The dimensions of another, alike beautiful, and more luxuriant, with the 

 colours finely contrasted, were no larger. — PI. X. 



The head survives its fall for a short time. It generally wastes away 

 suddenly, without falling. Likewise its decomposition is rapid. Though 

 many have wasted or fallen in the course of a night, none are to be dis- 

 covered at the bottom of the vessel next morning. 



From the transparent cylinder now remaining, the summit appears to 

 have been penetrated by a prolongation from below the disc : but the 

 point of union with any internal pith or medullary matter is imperceptible 

 during the hydra's life : Nor is this same hydra retractile, as already ob- 

 served, there being no vacuity for its reception. 



The nascent bud rises within the hollow tube, to replace the fallen 

 hydra, precisely in the same manner as that of the Tttbularia indivisa. 

 Those of largest size after protruding from the extremity, but before burst- 

 ing their involucrum, are twice the diameter of the stalk. The new tube 

 sustaining the regenerated hydra, though often much smaller than the 

 stalk to which it is united, speedily expands as the head advances. Its 

 delicate and pellucid red is finely contrasted with the dark umber of the 

 older parts. 



Much of the colour, size, and general aspect of specimens, depend on 

 age ; but as the new hydrise do not exceed the size of their precursors, the 

 proportion of the organic to the inorganic part is certainly diminishing, 

 because every addition to the latter is permanent ; and every regeneration 

 of the former is transient : Neither is the evolution of additional hydrae to 

 be compared with the multitude of the other parts. 



The generation and display of the embryo may be governed by the 

 same rules which predominate in the preceding species. 



A beautiful group of six or seven specimens, chiefly two inches and 

 a half high, bore numerous hydrae on the 12th of February. All had 

 fallen in three days. But in other twelve, many new heads were 



