Let us interrogate scientific opinion a little further on this question of sensibility. Is there any difference in animals as regards susceptibility to pain? Dr. Anthony says that we may take the amount of intelligence in animals as a fair measure of their sensibility--that the pain one would suffer would be in proportion to its intelligence. Dr. Rutherford, Edinburgh, never performs an experiment upon a cat or a spaniel if he can help it, because they are so exceedingly sensitive; and Dr. Horatio Wood, of Philadelphia, tells us that the nervous system of a cat is far more sensitive than that of the rabbit. On the other hand, Dr. Lister, of King's College, is not aware of any such difference in sensibility in animals, and Dr. Brunton, of St. Bartholomew's, finds cats such very good animals to operate with that he on one occasion used ninety in making a single experiment. Sir William Gull thinks "there are but few experiments performed on living creatures where sensation is not removed," yet Dr. Rutherford admits "about half" his experiments to have been made upon animals sensitive to pain. Professor Rolleston, of Oxford University, tells us "the whole question of anaesthetizing animals has an element of uncertainty"; and Professor Rutherford declares it "impossible to say" whether even artificial respiration is painful or not, "unless the animal can speak." Dr. Brunton, of St. Bartholomew's, says of that most painful experiment, poisoning by strychnine, that it cannot be efficiently shown if the animal be under chloroform. Dr. Davy, of Guy's, on the contrary, always gives chloroform, and finds it no impediment to successful demonstration, Is opium an anaesthetic? Claude Bernard declares that sensibility exists even though the animal be motionless: "_Il sent la douleur, mais il a, pour ainsi dire, perdu l'idee de la defense._"[A] But Dr. Brunton, of St. Bartholomew's hospital, London, has no hesitation whatever in contradicting this statement "emphatically, however high an authority it may be."