ANTHOZOA HYDROIDA. 9 



summary of their observations.* The ripe ovule or bud, 

 discharged from its matrix, settles and fixes itself to the site 

 of its future existence by minute fibres which pullulate from 

 the under-side, while, from the opposite pole, a papillary cone 

 shoots up to a height determined by the law which regulates 

 the peculiar habit of the species. The upward growth is 

 then arrested, and the apex becomes enlarged and bulbous. 

 The structure of this rudimentary shoot is at first apparently 

 homogeneous, but very shortly the separation between the 

 sheath and the interior pulp begins to be defined, and is made 

 hourly more apparent by the pulp retreating inwards, be- 

 coming darker and more concentrated. That portion of it 

 in the bulbous top of the shoot goes on to further conden- 

 sation and development ; and as it enlarges, so in proportion 

 does the horny cuticle that covers it expand apace until it has 

 gradually evolved into one or two cells, which are still closed 

 on all sides. The dark body of the polype is apparent 

 through the thin and transparent parietes, and from its su- 

 perior disk there are now to be seen some minute tubercles 

 or knobs protruding, which, becoming insensibly but steadily 

 more elongated, constitute the tentacula of the polype, — 

 now nearly ready for a more active life. By an extension of 

 development, or by a process of absorption not well under- 

 stood, the top of the cell is at length opened, the polype dis- 

 plays its organs abroad, and begins the capture of its prey, for, 

 unlike higher organisms, it is, at this the period of its birth, 

 as large and as perfect as it ever is at any subsequent period, 

 the walls of the cell having become indurated and unyielding, 

 and setting a limit to any further increase in bulk. The 

 growth being thus hindered in that direction, the pulp, in- 

 cessantly increased by new supplies of nutriment from the 

 polype, is constrained and forced into its original direction, 

 so that the extremities of the tube, which have remained soft 

 and pliant, are pushed onwards, the downward shoot be- 

 coming a root-like fibre, and the upper continuing the poly- 

 pidom, and swelling out as before, at stated intervals, into 

 cells for the new development of other polypes. 



* Sec Couch, Com. Fauna, iii. p. 7 ; Zoologist, i. p. 206-7 ; Ann. Nat. Hist. xv. 

 p. 163. 



