454 RECORD OF CURRENT RESEARCHES RELATING TO 



present ; in other words, closely allied species may or may not be 

 provided with them, (c) They are very similar to the yellow cells 

 found in the Eadiolaria, and these, as is known, are regarded by 

 Cienkowsky as very lowly vegetable parasites, (d) It seems more 

 than probable that the investing membrane is formed of cellulose. 



The authors then pass to a consideration of the structure of the 

 icall (Mauerblatt) and of the disk-like foot : these, just like the oral 

 disk and the tentacles, are closely allied in anatomical structure ; the 

 greater part of the ectoderm consists only of an epithelial layer, and 

 while the stinging and sensory cells decrease, the ciliated and the 

 glandular cells increase in number. The mesoderm is thick, and 

 consists of a number of layers of fibrillte ; in each layer the fibrill^e 

 run parallel to one another, and the separate layers are very closely 

 interwoven ; the supporting lamella is continued into inwardly 

 projecting folds of various heights, on some of which smaller folds 

 are a^ain developed. The endoderm has much the same character as 

 before, but at certain points its muscular layer is very greatly de- 

 veloped, and so gives rise to the circular muscle of Eotteken. As 

 seen in Tealia this structure has the following characters : — a longi- 

 tudinal section reveals the presence of a strong process of the body- 

 wall which projects into the coelenteric cavity and forms, not far 

 below the tentacles, a closed ring or circular welt ; the central por- 

 tion of this is occupied by a cord of connective tissue, and from its 

 surface there are given off delicate laminae, which are beset with 

 secondary and tertiary lamellae, and are held together like the leaves 

 of a book. These are covered by circularly set muscular fibres, while 

 the whole is covered by an endodermal epithelium, which, like the 

 other parts, is separated at points for the passage of the septa ; the 

 object of this arrangement, which is also to be found in Actinoloba 

 dianthus, is evidently to further the drawing of the wall of the body 

 over the more sensitive oral disk and tentacles. 



The marginal saccules ("bourses marginales") are also found in 

 some few Actiniae ; they form a circle of small spherical projections 

 set just below the outer circlet of tentacles, and in Actinia mesemhry- 

 anthemum they are to be distinguished by their blue colour. These 

 have been by numerous authorities (Schneider and Eotteken, Dana, 

 and Duncan) regarded as eyes ; Ludwig looks on them as urticating, 

 and Korotneff as tactile organs. Our authors look on them as 

 nematophores (urticating batteries), and thus describe their struc- 

 ture : the endoderm and mesoderm have the same structure as in the 

 body-wall, but the ectoderm is thickly laden with urticating cells on 

 its surface, and a nervous layer is developed in it. The authors 

 point out the value of the position which they occupy in the animal, 

 and further offer some criticisms on the observations of earlier writers. 



The next structure in the body- wall which is described are the pores 

 (cinclidfis, Gosse) ; these appear to be special means, not provided 

 with any sphincters, by which a communication is effected between 

 the interior of the body and the external medium. 



Coming now to the oesojyJiagus the authors direct attention to the 

 elongated cleft which forms the mouth, and which has on either side 



