Note 239 — Chapter II · DEDUCTIONS FROM GENERAL LAWS.

Even so eminent an investigator as Goltz has fallen into this confusion. He introduces an experiment to prove that the brainless frog is insensible to pain by the words “when an animal, placed under circumstances which would be very painful, makes no movement, although quite capable of moving, the least we can say is that it is improbable that the animal has sensation” (Nervencentren des Frosches, p. 127). I need not discuss the proof itself, having already done so in Nature, Vol. IX. p. 84. The point to which I wish to call attention is the confusion of insensibility in general with insensibility to pain.