418 Prof. G. J . Allman^s Biological Contributions. 



So exceedingly mutable is Corynactis viridis, perpetually ex- 

 hibiting some new and strange form, according to the state of 

 contraction in which it may happen to present itself, that all at- 

 tempts to limit its figure in description would be vain. At one 

 time it will assume the appearance of a narrow cylindrical stem 

 fixed by one extremity, and bearing upon the opposite a fiattened 

 circular disc attached to the stem like the blade of a peltate leaf 

 to its petiole. Sometimes a contraction will occur in the centre 

 of the body so as to cause the animal to present somewhat the 

 appearance of an hour-glass. Again, the central part of the ten- 

 tacular disc will be forced forwards into an elongated conical pro- 

 jection bearing the two outer circles of tentacula around the mar- 

 gin of its base, and with the mouth elevated upon its apex ; this 

 occurs without any eversion of the stomach. In short, the strange 

 shapes assumed by this protean polype are innumerable and al- 

 together beyond the domain of description (fig. 1). 



With the exception of the tentacula, whose structure is pecu- 

 liar, the anatomy of Corynactis would appear to diff'er in no es- 

 sential point from that of Actinia ; the structure of the tentacula 

 however is such as to demand here a moment^s attention. The 

 tentacula of Corynactis, like those of Actinia, are tubular, and com- 

 municate freely with the interseptal spaces ; they are however 

 imperforate at the free extremities, terminating there in little 

 spherical capitula, into which the tube of the stem penetrates 

 for some distance. Imbedded in the substance of these capitula 

 are certain highly curious organs ; they are of two kinds : one 

 consists of elongated ellipsoidal or fusiform bodies which are co- 

 piously scattered through the entire substance of the capitulum, 

 and which appear to be formed of a filament rolled into a close 

 helix and enveloped in a delicate transparent capsule (fig. 3) . 



The other set of bodies contained in the capitulum are larger 

 and not so numerous. They are transparent elliptical capsules 

 with a very long filament coiled up within them (fig. 4) . Many 

 project beyond the capitulum, causing this organ to present 

 under a high power of the microscope a somewhat hispid surface. 

 When liberated from the tentacula in the recent zoophyte, a very 

 remarkable phsenomenon is presented; the capsule opening at 

 one extremity gives exit to the contained filament, which uncoil- 

 ing itself as it escapes is rapidly shot across the field of the mi- 

 croscope (fig. 5). A spiral groove with approximated coils may 

 then be traced along the entire length of the exposed filament 

 (%.6). 



On a subsequent examination of specimens which had been 

 preserved for more than a year in spirits, a new feature in the 

 filament of the capsule was detected, The spirits had so acted 

 on it as to develope its real nature, and render manifest a much 



