. A text-book of human physiology . lls. If thisbe true, the neuron theory cannotbe maintained in any form. Butsince much remains yet to becleared up in regard to this ques-tion, and since different facts of ex-perimental physiology which Bethehas advanced in support of hisview (cf. page 575) really admitof another theoretical construction,the objection last urged against theneuron theory can scarcely yet beaccepted as conclusive. At present we may view thestructure of the nervous systemsomewhat as follows: The nervecells give off several processes, one or more of which become the axis cylinde
. A text-book of human physiology . lls. If thisbe true, the neuron theory cannotbe maintained in any form. Butsince much remains yet to becleared up in regard to this ques-tion, and since different facts of ex-perimental physiology which Bethehas advanced in support of hisview (cf. page 575) really admitof another theoretical construction,the objection last urged against theneuron theory can scarcely yet beaccepted as conclusive. At present we may view thestructure of the nervous systemsomewhat as follows: The nervecells give off several processes, one or more of which become the axis cylinders of nerve fibers. These consist offine fibrils which pursue a separate and unconnected course in the nerve fiber,oftentimes penetrate the nerve cell and there—in the invertebrates, but not inthe vertebrates—form a real network. These fibrils anastomose freely outsidethe nerve cells, and al-^o within the cells in the invertebrates, and thus consti-tute a possible path for the transmission of stimuli from one cell to the Fig. —Golpi network about a cell of thenucleus of the dog, after Bethe. 562 PHYSIOLOGY OF THE NERVE CELL AND THE SPINAL CORD It must be observed, however, in this connection, that our knowledge con-cerning the finest structure of the nervous system, especially in the vertebrates,is still too meager to admit of any one satisfactory or conclusive view, § 2. THE STRUCTURE OF THE SPINAL CORD i A cross section of the spinal cord (Fig. 254) shows the central gray matterwith its contained nei-ve cells, and surrounding it the white matter made upof nerve fibers. The anterior longitudinal or median fissure (a) and the pos- r h
Size: 1356px × 1844px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
