Reticular theory versus neuron theory in the work of Camillo Golgi.

In 1873 Golgi invented a revolutionary method for microscopic research of the nervous system, based on a particular technique for staining nerve cells, which came to be known as "black reaction". Thanks to this method, he was able to provide a thorough and precise description of nerve cells in various regions of the cerebro-spinal axis, clearly distinguishing the axon from the dendrites. He drew up a new classification of cells on the basis of the structure of their nervous prolongation, and he criticized Gerlach's theory of the "protoplasmic network". Golgi claimed to observe in the gray matter an extremely dense and intricate network, composed of a web of intertwined branches of axons coming from different cell layers ("diffuse nervous network"). This structure, which emerges from the axons and is therefore essentially different from that hypothesized by Gerlach, appeared in his view to be the main organ of the nervous system, the organ that connected different cerebral areas both anatomically and functionally by means of the transmission of an electric nervous impulse. Golgi's reticular theory, along with the other reticular theories of the nervous system prevalent at the end of the nineteenth century, had in a certain sense overturned the 'atomistic-reductionist' principle that lay behind the cell theory. These theories were in fact based on a holistic model, according to which the cerebro-spinal axis was considered to be a continuous structure, and its functions the result of a collective action. At the end of the 1880's, Ramon y Cajal began to elaborate the neuron theory, using Golgi's microscopic technique. Golgi, however, did not accept this theory, and a controversy arose between the two scientists that was not put to rest even after the rivals were both awarded the Nobel Prize in 1906. If we look at the reasons for which Golgi opposed the neuron theory, we can see that they derived not so much from disagreement over the actual data observed, as from a different way of conceiving the anatomo-physiological architecture of the nervous system: Golgi appeared to support a holistic conception of the nervous system, the same that lay behind the theories of the opponents to cerebral localization, whereas Cajal and the 'neuronists' embraced an 'atomistic-reductionist' assumption, according to which the nervous system is made up of the sum of just so many neurons, each of which is an anatomical, functional, and embryological individuality, and not merely a <> in a network of nervous filaments.