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at the part for the supply of which they are designed. They then split into numerous branches which communicate with each other, and again subdivide and rejoin, their communications appearing to multiply as they become more minute; so that every part of the body has a kind of network of nerves, which is minutë in proportion to the susceptibility and sensibility it possesses."

debit This general and imperfect sketch of the anatomy of the nervous system, relates only to what may be discovered by our unassisted sight. If by means of the microscope we endeavour to observe the ultimate nervous fibres, persons in general are as inuch at a loss as when by the same means they attempt to trace the ultimate muscular fibres.

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from a nervous packet, in the i, manner before mentioned, though too minute to admit of further subdivision, appear by the microscope to be themselves packets of smaller threads. It is generally asserted by microscopical observers, that the nerves and medullary matter of the brain and spinal marrow are the same, and are composed of very minute fibres. Fontana speaks confidently on this point si and he further says, that he has seen these nervous : fibres regenerated in the medium which has been formed to unite a divid.) ed nerve. , He describes the nervous fibres in every part of the nervous system as cylindrical, pursuing a slightly undulating course, and being in a considerable degree transparent.

transparent. He states also that they are larger than the ulti mate fibres of muscles.

Microscopical obseryers also tell us, that

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· The vital organs are required to carrý on their functions with a degree of regularity and order, under the varying circumstances of life; and the possession of a distinct nerve may enable them to continue their functions without so materially participating in the disturbances of the animal system, as they must otherwise have done : yet the munerous connections of the visceral with the animal nerves must render both participators in each other's disorders.

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The nerves, then, may be said to proÇeed from the brain, medulla spinalis, andi visceral nerve, to all parts of the body for their supply. In thus expressing a fact, however, we should guard against an idea which the analogous distribution of

arteries is apt to engender. Arteries become minute in proportion as they send off branches, whilst on the contrary, the branches of nerves are often larger than the trunk from which they proceeded. It is no unfrequent occurrence for malformed children to be born without a brain, yet with a perfect nervous system. The most rational idea, therefore, we can entertain on the present subject, is, that the nerves are formed in the parts where we find them, and that they are connected to those parts of the organs from which we are accustomed to say they proceed.: Nerves are vascular,; andwel can inject them with subtile injections. si

The nerves, then, proceeding froin, or being connected with the brain, metulla spinalis, and visceral nerve, may be tracedo ramifying throughout the body in the manner already mentioned, till they arrive

at the part for the supply of which they are designed. They then split into numerous branches which communicate with each other, and again subdivide and rejoin, their communications appearing to multiply as they become more minute; so that every part of the body has a kind of network of nerves, which is minute in proportion to the susceptibility and sensibility it possesses.

il' is This general and imperfect sketch of the anatomy of the nervous system, relates only to what may be discovered by our unassisted sight. If by means of the microscope we endeavour to observe the ultimate nervous fibres, persons in general are as inuch at a loss' as when by the same means they attempt to trace the ultimate muscular fibres.

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