Zoophytes. 277 



they are long, slender, and terminate at each end in a sharpened point, 

 at the base of which is a prominent rim ; the terminations thus re- 

 semble the pointed stopper and neck of a decanter. Between the ex- 

 tremities the body is straight ; but there are on different parts minute 

 cells, sometimes arranged in pairs, sometimes in circles, and occa- 

 sionally in a spiral manner. If still further decomposed, these bodies 

 become reduced in size, and altered in shape, so as to resemble mi- 

 nute Florence flasks, and finally become resolved into minute globular 

 cells, which constitute the ultimate structure of the membrane. The 

 union of these cells is of the most intimate kind, for with the most 

 powerful and varied lights their points of union could not be detected, 

 till they had become partially decomposed. The dark and light lines 

 with which the membrane is striated, are formed by the more close 

 or loose aggregation of these bodies, as was proved in their decom- 

 position. 



The membrane of the axis it is not always easy to demonstrate ; 

 sometimes it is very clearly to be seen, and so loosely attached that it 

 may be torn off, either with a knife or by the fingers ; at others, so 

 firmly attached and obscure, that its existence would be denied but 

 for its occasional well-marked presence. When the rugae are well 

 marked the membrane is easily observed ; when the axis is polished 

 it is very obscure, and is more or less marked, as one or the other pre- 

 ponderates. When the rugae are well marked, they appear to be 

 formed of.hollow tubes, which communicate with the tubes of the 

 fleshy bark. These tubes can never be seen to advantage, and fre- 

 quently cannot be seen at all, unless the specimen be examined in a 

 living state. This membrane is also fibrous, and rends freely in a 

 longitudinal direction. It is longitudinally striated with light and 

 dark lines, as is also observed in the membrane of the bark. The 

 resemblance between these membranes is very great ; both are longi- 

 tudinally striped, both have oval openings, and both have the same 

 ultimate structure. The structure, however, of the membrane of the 

 axis, from its being so firm and horny, is not so clearly to be noticed 

 as of the membrane of the crust. When it is but loosely attached it 

 is observable under the microscope, but it becomes more obscure as 

 its attachment becomes firmer, and when the axis is polished it is not 

 observable at all. 



At certain periods, which seem favourable to the growth of this spe- 

 cies, when it rapidly increases in size and height, the branches, 

 especially the youngest, are very frequently disfigured with large glo- 

 bular protuberances. These excrescences are to be found at all sea- 



