394 NOTES AND MEMORANDA. 



In a slightly more advanced stage another envelope, in the 

 form of a brown horny capsule, begins to be secreted be- 

 tween the proper wall of the zooid and the external gelati- 

 nous investment. It is at first thin and smooth, but it 

 gradually acquires considerable thickness, and becomes raised 

 on its outer surface into ridges enclosing hexagonal spaces. 



In this stage the capsule has become too opaque to admit 

 of a satisfactory view into its interior ; but if the capsule be 

 carefully opened its contents may be liberated so as to render 

 apparent their real nature. It will be then seen that these 

 consist of a minutely granular semifluid plasma surrounding 

 the ^^nucleus," which has much increased in size and occu- 

 pies a large portion of the cavity of the capsule. The con- 

 dition of the contractile space could not be determined ; it 

 has probably altogether disappeared. 



In a further stage the " nucleus " has undergone an im- 

 portant change ; for, instead of the long cylindrical form it 

 had hitherto presented, it has become irregularly branched, has 

 acquired a softer consistence, and has moreover broken itself 

 up into two or more pieces. This change in the "nucleus" 

 is invariably accompanied by the appearance of nucleated 

 cell-like bodies, which are scattered through the corp uscula 

 plasma which had filled the rest of the capsule. They are 

 of considerable size, of a spherical form, and with their 

 nucleus occupying the greater part of their cavity, and 

 having its nucleolus represented by a cluster of granules. 



In other capsules, apparently the more advanced, no trace 

 of the so-called nucleus of the vorticella body could be de- 

 tected, and it seems to be entirely replaced by the spherical 

 nucleated cells, which had now still further increased in 

 number. It is impossible not to regard these cells as the 

 result of the disintegration of the nucleus, and the conclu- 

 sion is a legitimate one, that they are finally liberated by the 

 natural dehiscence of the capsule, and become developed 

 into new vorticellidans. 



3. On the Structure of Edwardsia. By Prof. Allman. — The 

 structure of this beautiful little actinozoon dififers in many 

 important points from that of both the zoantharian and alcy- 

 onarian polypes. It was shown that just within the mouth 

 the walls of the stomach-sac project into the cavity of the 

 sac in such a way as to form eight complicated frill-like 

 lobes ; that the eight vertical, radiating lamellae which pro- 

 ject into the body cavity from the outer Walls, and are com- 

 posed of parallel -longitudinal fibres enclosed between two 

 membraneous layers, do not reach the stomach-sac in any 

 part of their course, and that eight strong muscular bundles 



