Page:Philosophical Review Volume 1.djvu/424

408 to most nerves. The microscopic nature of these ultimate fibrils is also known. If, then, minute specific nerves of pain exist throughout the body and are gathered up into various nerve trunks, the fact that most sensory nerves do give some pain can no longer seem remarkable, or be counted as evidence that pain is an inseparable or general attribute of the other senses.

The fact that pain rises from intense stimulation of most sensory organs, and that the specific quality of the senses disappears, or apparently is transformed into pain with increased violence of stimulation, is, at first sight, also a pertinent matter. For example, the blinding of sight and the alleged blending into pain under prolonged excitation of violently intense light, looks like a single process passing from one phase into another, rather than like two separate processes. But it is well known that every nerve has its range of excitation. The ear will not respond with sound to a too slow rate of vibration nor to a too rapid rate. If there were fit reasons why it would be better for the nerves of pain to respond to a more violent range of excitation than that which the nerves of the other senses could endure, this fact would throw light on the origin and function of Goldscheider's pain nerves, and also make clear the phenomenon in question. From the theories, which we shall come to later, of the benefits of pain as a warning against violent and injurious influences, this would seem to be the very arrangement and relation between pain and other nerves which most fits both plausibility and the facts. The nerves of sight, sound, heat, and so on, would according to this respond throughout the range to which they had been differentiated. When the more violent range was reached which was injurious to them and beyond which they could not perform their function, there the sight would cease, and the nerves of pain would take up the functions to which they had peculiarly developed because of the fact that they could endure them with benefit to the creature from their warnings. Under such an arrangement it would not be necessary that the two ranges, say of sight and of pain, should wholly exclude each other. It would be well for the warnings to begin before sight was entirely destroyed. Thus the two processes