HARDWICKE'S SCIENCE-GOSSIP. 



59 



branch is shown in vertical section, with (e) a polype 

 in its cellj'and (d) an empty cell. 



Fig. 31. Isis hippuris, x 5, vertical section. 



" The structure of the axis of the Gm-goniada" 

 says Quekett, in his "Lectures on Histology," 

 " has been the subject of much controversy. Many 

 authorities consider it to be inorganic. There cau, 

 however, be no doubt that, although the polypes 

 do not form the axis, tbey are mainly concerned in 

 preserving its vitality, and, as long as the polypes 

 are alive, changes, both in the interior and on the 

 exterior of the axis, are continually going on;" 

 and he mentions a specimen of Gorgonia flabell urn, 

 in the museum of the Royal College of Surgeons, 

 in which Nature has repaired an extensive fracture, 

 " nearly across the centre." 



In some species the axis is composed of con- 

 centric laminae of brown horn ; others, as G. spiralis 

 (fig. 33), show, not only concentric laminse of horn, 

 but a number of large radiating lines, which look 

 like tubes, but are, in reality, connected with the 

 spines seen on the surface. 



In G. petechialis (fig. 32) it is chiefly composed 

 of spicula, so arranged as to leave a number of 

 large canals, which run from one end of the axis to 

 the other; and the spicula near the surface are 

 much larger than those in the centre. 



In Melitcea ochracea, which is jointed like Isis 

 hippuris, the, horny matter is so small in quantity 

 as only to suffice to hold together the numerous 

 spicula of which the calcareous part of the axis 

 is composed. 



In Corallium rubrum, the common red coral of 

 commerce, the axis is very dense, and capable of 

 taking a high polish ; .but there is abundant evidence 

 to prove that, even solid as it is, it was originally 

 composed of spicula. J 



Fig. 32. Transverse section of a segment of axis of 

 Gurgonia petechialis, x 45. After Quekett. 



Fig. 33. Transverse section of a segment of axis of 

 Gorgonia spiralis, x 45. After Quekett. 



The "spicules" of our cabinets are chiefly ob- 

 tained from the dried crust or ccenosarc, although 

 they abound in all parts of the zoophyte, and when 

 carefully selected and skilfully mounted they are 

 beautiful objects for the microscope : the forms are 

 so distinct from each other that it has been thought 

 that by a careful examination a classification of 

 varieties may be some day based upon them. The 

 figures 34 to 42 are of " Gorgonia spicules," drawn 

 under the microscope ( x 75) from a superb set 

 prepared by Mr. Cole, of St. Domingo Vale, Ever- 

 ton, Liverpool, which will shortly find a suitable 

 resting-place amongst the treasures of the Quekett 

 Microscopical Club. 



