THE NERVES OF THE CAPILLARIES, WITH REMARKS ON NERVE-ENDINGS IN MUSCLE : A NEW THEORY OF LYMPH-FORMATION AND OF GLANDULAR SECRETION.
1. The endings of the motor nerves in striped muscle remain on the outside of the sarcolemma. Aside from the surfaces of contact of muscle and nerve fibre, the end fibres are covered down to their tips with the sheath of Schwann and are provided with nuclei. The precise condition of things at the places of contact of muscle and nerve is an unsolved problem of histology. 2. The ivy-like or festooned arrangement of motor nerves in the frog's muscle has been misinterpreted. Properly interpreted it demonstrates that the nerve fibres that are to influence the muscle fibre are not naked and that they need not be end fibres. It shows that mere contact between muscle fibre and nerve fibre is all that is necessary. 3. The sheath of Henle in the frog and in the smaller muscle fibres of the snake is open, thus permitting escape of the cerebrospinal fluid. 4. In other animals Henle's sheath extends over the end fibres of the motor nerve and the cells lining it envelop the end fibrils. I find that the so-called "Sohlensubstanz" of Kühne is derived from the cells of Henle's sheath. 5. The terminal nerves in smooth muscle form a network entwining the bundles of muscle fibres. I consider it improbable that each plain muscle fibre has a special terminal nerve fibril. 6. In muscular tissue fine non-medullated nerves, probably belonging to the centrifugal, vasomotor system, proceed from the fasciculi of motor nerves. These nerves can be traced directly to a network of nerves surrounding the capillaries. From this network fine, nucleated, nerve fibres pass to the walls of the capillaries, with which they are very closely united. 7. The nerves supplying the capillaries connect also with sensory nerves and with nerves surrounding the larger blood-vessels, both arteries and veins. 8. The branches of the chorda tympani in the submaxillary gland do not pass to the gland cells, but they terminate on the capillaries. 9. In muscular and glandular tissues-and perhaps throughout the body-there is a vast peripheral nervous plexus belonging to the capillary blood-vessels. These nerves of the capillaries, which may perhaps be regarded as nutritive nerves, regulate the production and transudation of lymph, and are concerned in the mechanism of glandular secretion. They may be called into activity both by peripheral influences and by impulses received from the central nervous system and the sympathetic ganglia. They may influence, through their connections with the vasomotor nerves on the arteries and veins, the blood supply to a part.
Sihler
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C
Cleveland, Ohio.