. Text book of vertebrate zoology. Vertebrates; Anatomy, Comparative. Fig. 71. Pa- cinian corpuscle. //, axis cylinder of nerve. birds, two or more biscuit-shaped cells are included in a connec- tive tissue, while the connecting nen'e becomes flattened out into disks between each two cells. A more complicated type is found in the corpuscles of Vater or Pacini,— elliptical structures composed of layers of cells like the layers of an onion, into the centre of which projects the axis cylinder of a sensory nerve. Under the heading of tactile cor- puscles (Wagner's or Meissner's corpuscles) are inc
. Text book of vertebrate zoology. Vertebrates; Anatomy, Comparative. Fig. 71. Pa- cinian corpuscle. //, axis cylinder of nerve. birds, two or more biscuit-shaped cells are included in a connec- tive tissue, while the connecting nen'e becomes flattened out into disks between each two cells. A more complicated type is found in the corpuscles of Vater or Pacini,— elliptical structures composed of layers of cells like the layers of an onion, into the centre of which projects the axis cylinder of a sensory nerve. Under the heading of tactile cor- puscles (Wagner's or Meissner's corpuscles) are included club-shaped aggregations of cells, around which are coiled the terminal fibrillae of a nerve. These last are scattered all over the body in the amphibia, but are more restricted in their distribution in the higher groups. Among tactile organs must also be enumerated the long facial hairs (vibrissse) of mammals, the base of each being surrounded by a network of nerves. Besides these special tactile organs there are numerous free nerve terminations in the epi- dermis of all vertebrates from cyclo- stomes to mammals to which sensory functions must be ascribed. The ears in all vertebrates are paired structures on either side of the head between the seventh and ninth nerves. In the most highly developed ears three portions are to be distinguished, — inner, middle, and outer, — the first of which only is sensory and essential, and is the only part occurring in the fishes;. Fig. 72. Meissner's corpuscle from human finger, after Law- dowski from Wiedersheim. a, fibrous tissue envelope; b, cor- puscle with its cells; «, entering medullated nerves; n', ramifica- tions of nerves; n", club-shaped nerve Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kingsley, J. S. (John Sterling), 1854-
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