subordinate one is sufficient to determine what is needed; such is the spinal cord, in the reflex actions discovered by Marshall Hall, such as sneezing, yawning, vomiting, the second half of swallowing, &c. &c. The will itself is present in the whole organism, since this is merely its visible form; the nervous system exists everywhere merely for the purpose of making the direction of an action possible by a control of it, as it were to serve the will as a mirror, so that it may see what it does, just as we use a mirror to shave by. Hence small sensoria arise within us for special, and consequently simple, functions, the ganglia; but the chief sensorium, the brain, is the great and skilfully contrived apparatus for the complicated and multifarious functions which have to do with the ceaselessly and irregularly changing external world. Wherever in the organism the nerve threads run together in a ganglion, there, to a certain extent, an animal exists for itself and shut off, which by means of the ganglion has a kind of weak knowledge, the sphere of which is, however, limited to the part from which these nerves directly come. But what actuates these parts to such quasi knowledge is clearly the will; indeed we are utterly unable to conceive it otherwise. Upon this depends the vita propria of each part, and also in the case of insects, which, instead of a spinal cord, have a double string of nerves, with ganglia at regular intervals, the capacity of each part to continue alive for days after being severed from the head and the rest of the trunk; and finally also the actions which in the last instance do not receive their motives from the brain, i.e., instinct and natural mechanical skill. Marshall Hall, whose discovery of the reflex movements I have mentioned above, has given us in this the theory of involuntary movements. Some of these are normal or physiological; such are the closing of the places of ingress to and egress from the body, thus of the sphincteres vesicæ et ani (proceeding from the nerves of the spinal cord); the closing of the eyelids in sleep (from the fifth pair of
