Human physiology : designed for colleges and the higher classes in schools and for general reading . NERVES OF TOUCH IN THE SKIN OF THE THUMB. termination of the nerves as seen through the microscope ina thin perpendicular section of the skin in the thumb. Thethree eminences in this figure are those of the papilla, as theyare termed, which you can see are arranged in curvilinear rows,if you look at the ball of the thumb. In Fig. 79 you see thissame loop-like arrangement in the nervous tubuli, as seenthrough the microscope, on the sensitive sac that lines thecavity of a tooth, the entrance for
Human physiology : designed for colleges and the higher classes in schools and for general reading . NERVES OF TOUCH IN THE SKIN OF THE THUMB. termination of the nerves as seen through the microscope ina thin perpendicular section of the skin in the thumb. Thethree eminences in this figure are those of the papilla, as theyare termed, which you can see are arranged in curvilinear rows,if you look at the ball of the thumb. In Fig. 79 you see thissame loop-like arrangement in the nervous tubuli, as seenthrough the microscope, on the sensitive sac that lines thecavity of a tooth, the entrance for the nerves and bloodvessels©f this sac being at the end of the root. 237. One very singular termination of the nervous tubuli, isin what are called Pacinian corpuscles, after Pacini, the firstmicroscopist that discovered them. They are found attachedto the nerves in the hand and foot more often than any where THE NERVOUS SYSTEM. 151 Pacinian corpuscles. Their office not 79. NERVES IN A TOOTH. PACINIAN CORPUSCLES. else. Their structure, which is seen in Fig. 80, A, highlymagnified, is very curious. They are attached to the branchesof the nerves on which they cluster by little peduncles orstalks. At a is the peduncle; b is the nervous fibre ortubulus; / is its termination in the corpuscle. The corpuscleitself is composed of layers of a very delicate fibrous membraneinclosing each other like the coats of an onion, to the numberof sometimes sixty, the inner ones, d, being closer together thanthe outer ones, c, are. In B is represented a portion of anerve of a finger, with clusters of these corpuscles of about thenatural size. Of what use these singular bodies are we knownot. But the fact that they are always found in certainregions of the body shows that they are placed there for somedefinite purpose. It has been supposed by some that they areminute electrical batteries, because they bear some resemblanceto the electrical organs found in some fishes. 238. Th
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