274 ZOOPHYTES. 



severed stern, may produce new shoots, ultimately bearing hydra, though 

 all the rest remain abortive. 



It is from this approximated congeries of tubuli that sections of the 

 stem resemble the most porous wood. 



Shoots sometimes issue both upwards and downwards, from very 

 vigorous sections ; nor are examples wanting of hydra being generated in 

 opposite directions from the same section. 



The inorganic parts diverge into many beautiful arborescent forms 

 among the Tubularise, Sertularise, Flustra, and Plumatella, dividing and 

 subdividing, after various arrangement, as boughs, branches, and twigs, 

 ultimately terminating in simple orifices, permanent cells, or deciduous 



bells. 



Throughout there is nothing representative of foliage ; but the vesicle 

 and the hydra may be compared to the pod, or the pericarp, and the flower 

 of plants. 



5. Hydra. — Zoophytes, it has been explained, consist of two distinct 

 parts, each with its peculiar qualities, — one being that where animation 

 resides, the other wherein it is not evident. In the former, animation is 

 demonstrated by spontaneous motion and activity ; by the discharge of 

 functions important for conservation of the individual, or for continuance 

 of the race ; which last, however, seems to be a physical result, not under 

 any control. None of these qualities are sensible in the inorganic portion, 

 which is nevertheless of indispensable use. Although void of action and 

 evident sensation, and also of external impressions, it seems susceptible of 

 nutrition, consequently of increment ; it is a real skeleton. 



The hydra or polypus is always in such a position as to be in imme- 

 diate contact with the circumambient element. Salubrity is derived from 

 its presence, and privation of it is followed by inevitable destruction. 



The hydra is also in immediate connection with the pith, occupying 

 all the tubular part of the skeleton, the outward or sustaining inorganic 

 portions, and its development from it in the regenerating Tubularia ifidi- 

 visa is exposed by the transparency of the summit of the fistulous stem. 



Perhaps the pith is consistent when in perfection, though resolving, 



