270 ZOOPHYTES. 



But the root of the fistulous, arborescent, foliaceous, and gelatinous 

 zoophytes, does not exhibit that distinct and proper organization to which 

 a similar purpose in the same extent can be ascribed. 



The Sertularian zoophyte, in its origin, diffuses a few minute radicles, 

 speedily disappearing, and just at that juncture when their presence might 

 begin to be held important. If the root of the Tubularia be prolonged, 

 it is apparently by descent of the stem, and owing to its fistulous forma- 

 tion, never spreading, nor does it pierce the substance to which it is applied. 

 That of the Flustra is the original foundation-cell of the specimen ; in all 

 this specific portion, the root, seems quite insignificant compared with the 

 dimensions of the rest in its advancing stages, — and inadequate to enable the 

 specimen to resist the turbulence of the fresh-waters, or the concussion of 

 the waves. On forcible divulsion of a specimen of the Sertularia argentea, 

 two feet high, a scale of only a line in diameter, separated from the sur- 

 face of the shell sustaining it. The root had occupied no more. 



Recalling the mode of perpetuation explained above, we find the 

 planula from the prolific vesicle contracting as a spherical segment ; that 

 the under surface breaks into radicles amidst an attenuating matter below, 

 circumscribed by a circular outline. The radicles being from four to 

 eight, are scarcely farther prolonged ; their extremities cleave into two 

 obtuse parts. At length as six or eight needles they radiate from the 

 centre to the marginal circle, but along with the dissipation of the diffu- 

 sing matter they also disappear. 



Possibly the nature of the root might be elucidated from the struc- 

 ture of the stem. Many species of the Sertularia show vigorous repro- 

 ductive energies; some are continually generating abortive filaments, 

 along with prolific cells. A tuft of considerable dimensions, resembling 

 mossy matter, always separates with the Sertularia (nemertesia) ramosa 

 when torn up from its foundation. In this species, it is to be observed, 

 the stem consists of an aggregate of numerous tubuli, insomuch that a 

 transverse section of the stem of an aged specimen offers a rude resem- 

 blance to the microscopic pores in thin slices of wood. Likewise prolific 

 vegetation is often ready to spring upwards from each of the sundered 

 tubuli. On divulsion of a specimen of this product, six inches high, rising 



