. Evenings at the microscope : or, Researches among the minuter organs and forms of animal life . Zoology; Microscopy; Microscopes. 172 EVENINGS AT THE MICROSCOPE. general surface of the body, and with long, delicate, mem- branous filaments (seta, often improperly called cilia), which are larger and much more delicate in structure than the ordinary hairs. The basal joint is greatly enlarged : if it be carefully removed from its connexion with the head, and broken open, it will be found to inclose in its cavity a still smaller chamber, with calcareous walls of a much more delicate character tha
. Evenings at the microscope : or, Researches among the minuter organs and forms of animal life . Zoology; Microscopy; Microscopes. 172 EVENINGS AT THE MICROSCOPE. general surface of the body, and with long, delicate, mem- branous filaments (seta, often improperly called cilia), which are larger and much more delicate in structure than the ordinary hairs. The basal joint is greatly enlarged : if it be carefully removed from its connexion with the head, and broken open, it will be found to inclose in its cavity a still smaller chamber, with calcareous walls of a much more delicate character than the outer walls. This internal cell is con- sidered by Mr. Spence Bate to be a cochlea,* from its analogy, both in structure and supposed use, to the organ so named in the internal ear of man and other vertebrate animals. It is situated, as has been said, in the cavity of the basal joint of the internal antennae, and is attached to the interior surface of its wall farthest from the median line of the Crab. It has a tendency to a spiral form, but does not pass beyond the limits of a single convolution. If this interior cell does indeed represent the cochlea of more highly-constructed ears, to which it bears some resemblance both in form and structure, then it seems to identify, beyond dispute, these inner or upper antennas as the organs of hearing. Now with this conclusion agrees well the manner in whichthe living animal makes use of the organs in ques- tion. The Crab always carries them erect and elevated; and is incessantly striking the water with them, with a very peculiar jerking action, now and then vibrating, and, as it has been called,"twiddling"them. These ,„ ,vb FE« ,m., f antenna, therefore, appear to be always on the watch: let * Cochlea, the Latin for Snail-shell, is the name given to one of the cavities of the ear, from its resemblance to the interior of a. snail- Please note that these images are extracted from scanned page images that may ha
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