312 BIRTH OF A PLANULE. 



though without my seeing it : and I sat down to 

 watch a vesicle. Presently one of the contained 

 worm-like gemmules began to elongate its body, and 

 to move slowly along the narrow neck of the bottle- 

 like vesicle, toward the mouth, with a steady progres- 

 sion, which the power I was using (220 diam.) enabled 

 me to see was ciliary. It soon began to emerge, the 

 soft shapeless body taking a globose form as it pro- 

 truded, and swelling upon the mouth of its prison, like 

 a large globular head of a decanter. (See Plate XX, 

 Fig. 6). As soon as it was well out, however, it took 

 a definite form, that of a sub-conical oval, of which 

 the larger end progressed foremost. Its length was 

 about -^ th of an inch, and its breadth about half as 

 much ; but as it moved, it became rather shorter. In 

 appearance it exactly resembled an Infusory animal- 

 cule, being of an uniform granular texture, and co- 

 vered with minute vibrating cilia in every part of its 

 surface. (Pig. 7). 



At first it revolved on its long axis, but presently 

 this action gradually ceased, and it proceeded steadily 

 in the same direction as it at first set out, until it had 

 reached about twenty times its own length, when it 

 came to a rest, about half an hour after its emergence ; 

 the vibration of the cilia still continuing. 



In an hour and a quarter the ciliary action was but 

 just discernible ; it had not moved from its place of 

 rest, though its whole mass slightly quivered and vi- 

 brated. The outline was now become ragged, and set 

 with minute clear globules projected and isolated, as 

 if the connecting gelatinous substance which bound 

 them together was dissolving. I was now called away, 



