Misceilaneous. 387 
On the Urticating Capsules of some Polypes and Acalephs. 
By Karu Mosivs. 
The urticating capsules are elastic vesicles, which may be compared 
with simple glands. They have a long efferent duct, which is pro- 
duced within their cavity, and is appended directly to the outer wall 
as an inversion of it. As the commencement of this duct bends at 
first inwards, then upwards and then again inwards, a threefold tube 
is produced—the aazal body, the innermost division of which passes 
over into the filamentous piece, the convolutions of which either 
surround the axial body or run down beside and below it. 
The capsular wall everts the duct suddenly by its contracting 
elasticity, whenever, being assisted by external pressure, it can over- 
come the extending resistance of the duct. 
The pressure of the capsular wall propagates itself over the whole 
of the duct through the fluid contents ; but its first everting action is 
exerted in front, at the angle where the middle tube of the axial 
body bends into the inner one. 
The duct is beset with spiral rows of hairs. As long as it remains 
within the capsule these are turned inwards and present a resistance 
to the pressure of the capsule, but when it is everted, they stand out 
and then increase its adhesive power. The everted ducts remain 
attached to surfaces with which they come in contact, and moisten 
these with their fluid contents. This produces an urticating pain on 
sensitive parts of the skin. 
Each capsule can only act once. As it remains connected with 
its everted duct, it is torn out of the skin as soon as the movements 
of the Polype retract its place of insertion. The lost capsules are 
replaced by new ones, which are formed below them. They are de- 
veloped in cells with granular contents and with one or more nuclei. 
The long cylindrical urticating capsules are at first bent in their 
formative cells, and only afterwards become extended. Large axial 
bodies appear earlier than the filiform end of the duct, which in 
immature capsules lies regularly twisted on the wall; in mature 
eapsules irregular bendings frequently interrupt the course of the 
ordinary spiral. 
Most of the capsules made use of by Polypes and Acalephs, pass 
with their food into their own stomachs. Perhaps, when there, they 
assist digestion. Some Sea-anemones form an envelope for them- 
selves of discharged capsules interlaced together. Many Polypes 
(Lucernarie, Actinie, Hydre) which change their places, employ 
urticating capsules during their progression, to enable their tentacles 
to adhere. As all rough contact induces the Ccelenterata to contract 
themselves, they discharge urticating capsules whenever they are 
subjected to an unfriendly attack; and thus these may serve them for 
defence. 
(These statements form the concluding summary of the results 
detailed in the author’s paper in the fifth volume of the ‘Abhandl. des 
naturwissenschaftlichen Vereins zu Hamburg,’ 1866, of which he has 
kindly sent us a copy.) 
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