The neurofibrillar structures in the ganglia of the leech and crayfish with especial reference to the neurone theory
Journal of Comparative Neurology
A previous publication treats irl detail of the fibrillar networks in the neuropil of the leech. In the present paper it is purposed to give a more general description of the fibrillar structures found in the nervous system of the leech and crayfish and t o point out the relation of these structures to the neurone theory. The neurone theory, grounded upon the fundamental researches of GUDDEN, GOLGI, and HIS, was first formulated by W A L D 7 Y E n ('91) in the following words : "Das
... : "Das Nervensystem bestcht aus zahlreichen, unter einander .anatomisch wie genetisch nicht zusammenhangenden Nerveneinheiten (Neuronen). " As WALI)EYER, VEKWORN, and NISSL have shown, the all-important point embraced in the neurone theory is not the anatomical independence of the nervous elements, but the assumption that the nervous system is entirely composed of cell individuals. Whether the processes of these cells are only in contact, or b y growing together have become continuous, is a secondary matter. Nevertheless, on the threefold evidence of histogenesis, neuropathology, and histology, most neurologists maintain that the nervous system is composed of anatomically independent, cellular units. I . Histogenesis. That the nerve elements develop from single neuroblasts and not from chains of cells was first asserted 158 JOURNAL OF COMPARATIVE NEUROLOGY.