THE ANATOMY OF ACTINIA MESEMBRYANTHEMUM. 217 



always open in water ; and it has this charming habit that if you 

 place it in a wine glass of sea water it at once lifts its disc to the 

 surface, so that by bringing a lamp over it you can throw the light 

 through a bull's-eye into the interior, and make out the relation of 

 the parts ; but, further, it will allow you to do what no other Actinia, 

 that I know of, will permit ; for with a sharp pair of scissors you 

 may cut off one of the tentacles, and it will hardly flinch ; if then you 

 quickly insert a piece of jeweller's fine gold wire into the hole thus 

 made, you will find that by help of the light falling on the wire, and 

 by watching the undulations of the septa as the wire moves them, 

 you will be able to follow and distinguish their several edges, while a 

 crochet needle or knitting pin inserted into the oral aperture will 

 reach the gold wire and settle, if you have any doubt of it, an extra- 

 ordinary question, which seems, strangely enoagh, to have puzzled 

 some Naturalists, namely, whether the aperture is closed at the lower 

 extremity of the cylinder or not ! 



A. dianthus in young specimens is very transparent at its sides and 

 base, and as both these last mentioned Actinice are easily obtained 

 along the coast from Weymouth to Swanage, and travel well, they 

 are most useful to the naturalist. 



There is another way of dealing with the two last named species 

 which only requires a quick hand and the arrangement of the various 

 septa, as shown in Fig. 1, to be carefully kept in view. It is to 

 extract through the side of the specimen one of the quaternary 

 septa. In order to find these you have only to look at the base (see 

 Fig. 5, pi. XI), or to trace down the external coat of the specimen the 

 primary septa which correspond with the large front tentacles and 

 with the knee-like projections on the oral aperture and are always 

 easy to see — on either side of this primary pair you will be always 

 sure of finding a quaternary pair d 1 , to c/ 4 in Fig. 1 — having found a 

 pair make two rapid longitudinal cuts with a sharp knife, one on 

 each side of the line, where the septum meets the epidermis, but not 

 so as to reach down to the base or up to the disc, and taking care to 

 miss the septum itself. Then with a pair of scissors make two deep 

 transverse cuts perpendicular to the others, and at each end of them, 

 so as to unite the two. This should free the septum if it is a 

 quaternary, and it can then be drawn out with forceps and examined. 

 The dotted lines in Fig. 1, pi. XI. show three of the cuts, the 

 other is hid from sight. Similar incisions may be made in the case 

 of secondary and tertiary septa when found, taking care only to limit 



