HARDWICKE'S S C IE NCE-GOSSIP. 



57 



connection with the vital tissue of the polype by a 

 kind of umbilical cord (k, I). In all the compound 

 Hydrozoa, the ovicapsules are deciduous, and Laving 

 performed their functions in relation to the develop- 

 ment of the new progeny, drop off like the seed- 

 capsules of plants. This phenomenon afforded to 

 the early botanists an additional argument in favour 

 of the relation of these ramified and rooted animals 

 to the vegetable kingdom." The modification in 

 the growtli of the coralline to form the ovicapsule, 

 has been compared by Professor Edward Forbes 

 with that "metamorphosis in flowering plants in 

 which the floral bud is constituted through the 

 contraction of the axis and the whorliug of the 

 individuals borne on that axis, and by their trans- 

 formation into the several parts of the flower." — 

 Vide " Annals of Natural History," vol. xiv., a.d. 

 1S44. 



Erom the Hydra-like compound polypes, with 

 their horny external skeletons, we pass on to the 

 class with internal skeletons, with which we are 

 more immediately concerned, the compound An- 

 thozoa {iivQoQ, a flower ; Z>S>ov, an animal). " Fixed, 

 compound polypes, with eight pinnate tentacles, 

 retractile in cells of a fleshy substance, strengthened 

 by calcareous spicula, and supported on a branched, 

 calcareous, firm or flexible axis. Genera, Gorgonia, 

 his, Melittea." 



We have seen how the poor naked solitary Hydra 

 stands related to the infinite multitudes of all the 

 class of compound creatures made more or less after 

 the fundamental idea of which he is the humble ex- 

 pression ; so, here also, as the starting-point of the 

 myriads of the Anthozoa we see standing in analo- 

 gous relation to them, a single, solitary animal- 

 flower, the polype Actinia, the homely familiar Sea- 

 anemone. The unclad Hydra shows no symptoms 

 of the sclerodermic covering (aicXijpbg, hard, dsp/ia, 

 skin, or hide) which will invest the composite forms 

 fashioned more or less after his image ; nor does 

 the soft Sea-anemone display any tendency to set 

 up the chitinous, horny, or calcareous sclerobasis 

 (o-fcX/jpoc, hard, fiaoiQ, foundation), which forms the 

 axis, the mainstay and support of his compound 

 representatives : indeed, the thin base-dise or foot 

 of the common actinia is as fatally vulnerable 

 as the heel of Achilles, while the other parts of 

 his body may be cut or torn with comparative 

 impunity. 



It would be beyond both the object we have in 

 view, and the limits of our space, to go into minute 

 details of the difference in the modes of growth and 

 life of the polypidoms of the Hydrozoa and the An- 

 thozoa, but we hope that no one will run away with 

 the impression that we wish to convey the idea that 

 a Sertularia is only a branching Hydra with a horny 

 case ; and that Gorgonia, and the rest of the Antho- 

 zoa, with their skeletons inside their ccenosarc 



(koivoc, shared in common, aafi, flesh) instead of 

 outside, are only Hydrozoa turned outside in : we 

 can only afford to speak in broad general terms ; for 

 exact and full details the student must refer to such 

 works as Johnston's " British Zoophytes," Hincks's 

 "Hydroid Zoophytes," Couch's "Fauna of Corn- 

 wall," Owen's " Anatomy of the Invertebrata," and 

 the writings of Van Beneden, Lister, Dalyell, Milne- 

 Edwardes, and others. Lister, in "Philosophical 

 Transactions, 1834" (quoted by Rymer Jones, 

 ''General Structure of the Animal Kingdom"), 

 gives a very full account (with illustrations) of 

 the development of the Hydrozoa. 



To many people these books are almost as inac- 

 cessible as the " Rig Veda " of the Brahmans, or 

 the "Tao-Te-King" of the Chinese sage "Lao-tse ";. 

 yet they may be dear lovers of Nature, yearning 

 with earnest longing to know something about the 

 miniature sea-firs and sea -willows, which the ocean 

 throws up in millions at their feet; so, for their 

 benefit, we here insert a long extract from John- 

 ston, on the growth of the Polypidom of the com- 

 pound hydriform polypes. 



"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 ap- 

 parently homogeneous, but very shortly the separa- 

 tion between the sheath and the interior pulp 

 begins to be defined, and is made hourly more ap- 

 parent by the pulp retreating inwards, becoming- 

 darker and more concentrated. That portion of it 

 in the bulbous top of the shoot goes on to further 

 condensation 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 

 superior 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 understood, 

 the top of the cell is at length opened, the polype 

 displays 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 wails 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, 



