INTRODUCTION. 
XXIX 
wisdom working to a given end by perfeetly adequate 
means. The ejeeted acontia, loaded with their deadly 
cnidie in every part of their length, earry abroad their 
fatal powers not the less surely, than if each had been 
provided with a proper tube leading from its free extremity 
to the nearest cinclis. 
The Cnidee. — I come now to describe those minute but 
potent organs which constitute the object of all the mecha- 
nism above described. Four distinct forms of these cap- 
sules have occurred to my investigations ; and these I shall 
treat of in turn. 
(1.) Chambered Cnidee [Cnidee cameratee). This is 
perhaps the most generally distributed form, as it is 
manifestly the most elaborately armed. It may be well 
examined in Caryophyllia Smithii. The globular heads 
of the tentacles seem, under pressure, to be literally com- 
posed of these capsules, the ends of which project side by 
side, as close as they can be packed, one against another. 
The form of these is long and slender, almost linear. The 
craspeda are also similarly studded with cnidee^ which are, 
however, of longer dimensions, and of fuller form. As I have 
seen no chambered cnid®, in any species, so large as these, I 
shall take them as a standard for description, alluding to 
those of other species only when they differ from these. 
They are perfectly transparent, colourless vesicles, of a 
lengthened ovate figure, considerably larger at one end 
than at the other (Plate XI. fig. 6). One of average 
dimensions measures in length *004 inch, and in greatest 
diameter *0005. In the larger (the anterior) moiety, is 
seen, passing longitudinally through its centre, a slender 
chamber, fusiform or lozenge-form, about ‘00015 inch in 
its greatest transverse diameter, and tapering to a point at 
each extremity. The anterior point merges into the "walls 
of the cnidee at its extremity, while the posterior end, after 
having become attenuated like the anterior, dilates with a 
fuunel-sliaped mouth, in which the eye can clearly see a 
double-infolding of the chamber-wall. After this double 
fold the structure prpceeds as a very slender cord, which, 
])assing back towards the anterior end of the capsule, winds 
loosely round and round the chamber, with some regadarity 
at first, but becoming involved in contortions more and 
more intricate as it fills up the posterior moiety of the 
cavity. The fusiform chamber appears to be marked on 
