ABSTRACT
The automatic activity of the nervous elements awakes at variable epochs, according to the precocity of morphological development of the elements. The manifestations of automatic activity in the brain follow by degrees the progress of physical development, and this in a very rapid fashion. Childhood and youth are the two phases of life during which the automatic activity of the cerebral elements reveals itself with the greatest energy. It is the period when memory has the greatest vigour, when the sensibility of the cerebral cell is most exquisite, either to feel the excitations which thrill through it, to retain them. The effects of progressive senility are marked by insensible gradations in human brains, by a slow, gradual enfeebling of the automatic activity of the elements. In proportion, then, as sensibility grows languid, and the faculty of erethism loses its energy in the elements of the sensorium, the external manifestations of the life of the brain undergo a parallel retrogressive movement.
