HYDllOID ZOOPHYTES. 49 



" Along with these, on the floor of the glass vessel, were 

 many minute animalcules, of an opaque-white hue, somewhat 

 Pl-anaria-like, which crawled slowly and irregularly, protrud- 

 ing the anterior portion of the body in a blunt point, but 

 often contracting the whole outline into a subglobose form. 

 These worm-like animalcules I found to be the primal form 

 of the young polype ; and though I have not been able to 

 trace the metamorphosis through every stage in the same 

 individual, the facts I have observed leave it indubitable. 



" I took two thin plates of glass, and suspended them by 

 threads in the vessel, near the bottom, horizontally, with a 

 view to obtain some of the embryos rooting themselves 

 thereon, which I might afterwards take out, to watch their 

 progressive development under the microscope. ]\Ieanwhile 

 I secured the first step in the inquiry, by opening with 

 needles some of the crowded vesicles of the adult poly- 

 pidom, from which I obtained some of the minute white 

 worms. In two or three days I drew out the plates of glass 

 and put them in shallow cells of sea-water, fit for the stage 

 of the microscope : I found upon them the young animals in 

 various stages. Some of the worms were yet vagrant, and 

 crawled freely about the surface ; others had selected their 

 position and were adherent, but still retained their power of 



