The branches of the s3mpathetic which pass to the different glandular organs also consist chiefly of fine nerve-fibres and fibres of Remak. In general there are more or fewer fibres belonging to the broad variety also present. In the substance of the organs they run in company with the blood-vessels and with the ducts of the glands, and appear to be chiefly distributed to these: at least no nerve-fibres have as yet been discovered run ning separate from the vessels or ducts in the parenchyma of the organ. In the finer rami fications of the nerves, the broader tubular fibres gradually disappear. The fine fibres also lose their distinct dark margins, and become pale and more or less indistinct. Their exact mode of termination has not been determined. Pappenheim, however, describes the nerves of the kidney as ter rninating in a looped arrangement. Small ganglia occur on the nerves distributed to many of the glands : they have been seen by Ludwig on the nerves of the kidney ; also by Pappenheim on the nerves distributed to the supra-renal capsules. Schaffner* has also ob served ganglionic corpuscles from which nerve-tubes proceeded, in the substance of the lymphatic glands. Small ganglia have also been described by Remak as occurring on the nerves distributed to the bronchi : they have also been observed by Kolliker. The latter observer believes that he has seen nerve-tubes arise from them.
From the observations of Purkinje* it would appear that numerous fibres of the sympathetic pass to the cerebro-spinal mem branes. In the dura mater of the cranium he describes the nerves as most abundant in the neighbourhood of the trunks of the three meningeal arteries. Most of them accom pany the vessels ; but there are also others which leave them and ramify in the mem brane. In the pia mater of the cerebellum the nerves which branch separately from the arteries are not so numerous as in the pia mater of the cord The nerves in the pons and cerebrum belong exclusively to the ar teries : no trace of nerve-fibres was seen in the choroid plexuses. Around the vena
Galeni magna they form a dense plexus which passes into the tentorium cerebelli, and seems to belong to it rather than to the venous system. The nerves in the pia mater of the cord unite with those of the cerebellum and pons. In the pia mater of the spinal cord the nerves are more abundant than in any other part of the cerebral membranes ; they run singly or in bundles of two and three ; others contain from thirty to fifty fila ments. Sometimes fibres leave the bundles, forming loops and returning to the same or to a different bundle. The largest bundles are situated near the anterior spinal artery, which they entwine; and some pass from this into the process of the dura inatet in the anterior fissure, and form loops in the same. Other large bundles, running mostly in a longitudinal direct'on, are situated near the ligamentum dentatum and posterior median line of the cord. Near the origins of the spinal nerves the bundles of sympathetic fibres are not so numerous and are also smaller. Some of these fibres spring from the cerebro-spinal nerves, and enter mdth the arteries through the intervertebral foramina. In the perito neum nerve-fibres have been described by Bourgery* as existing in considerable num bers. They have also been observed by Luschka.t Nerve-fibres are also abundant in the periosteum, both that which invests the shafts of the bones and the articular extremi ties of the same, as shown by the observations of Pappenheim.t They are chiefly situated in the outer part of the membrane, and either run in company with the vessels or are situ ated upon them. They terminate in loops. Nerves also exist, according to the same author, in the cellular tissue which surrounds the ligaments, penetrating these along with the arteries, and terminating in a series of plexuses and loops. In the tendons they are also sometimes present. Wherever (accord ing to Pappenheim) vessels pass to ligaments or tendons, nerves pass also.