And, referring to another experimenter, Dr. Crile, puts the case clearly:
"PAIN INCREASES (BLOOD)-PRESSURE. In four cases of trauma (injury), a rise of 20 to 40 was noted upon pressure upon a nerve. Even in a healthy person, pinching the integument was noted increase the pressure."[2]
[2] Crile "On Blood-Pressure," p. 341.
It would seem unnecessary to accumulate evidence regarding a physiological phenomenon so long and so firmly established. We may therefore take it for granted that in a living animal or in a human being, as a general rule, the irritation of a sensory nerve will cause a rise of blood-pressure.
Let us now suppose that an animal destined to be vivisected lies before us, "stretched" on the vivisection dog-board, so securely fastened that voluntary movement is almost impossible. An incision has been made in the neck, and in the principal artery has been inserted a part of a delicate instrument designed to indicate the fluctuations of the blood-pressure of the animal. The sciatic nerve has been laid bare; the animal is supposed to be under the influence of an anaaesthetic continuously administered, and if our imagination is vivid and our faith implicit, we may believe that no suffering will be felt. BUT HOW MAY WE BE CERTAIN? This question came up more than once before the Royal Commission on Vivisection. How can one tell that an animal may not be insufficiently anaesthetized IF IT CAN MAKE NO SIGN, WHEN ALL THE ACTS BY WHICH IT MIGHT EVINCE ITS SUFFERING ARE CAREFULLY RESTRAINED? The animal which lies before us cannot move; every physical movement is as far as possible totally suppressed. It cannot use its voice, for the trachea is cut and otherwise used. ARE THERE NO MEANS WHEREBY WE CAN TELL WHETHER THE ANIMAL IS SUFFERING what one of the Royal Commission called "a nightmare of suffering"?
The answer to this question has been given by some of the leading physiologists of England.
Dr. J. M. Langley, professor of physiology in the University of Cambridge, a Fellow of the Royal Society, gave explicit testimony on this point. His examiner was desirous of knowing upon what he would depend, other than upon the dose of the anaesthetic and watchfulness, if in the animal he could see nothing that would satisfy him.
"There is the state of the blood-pressure, which would indicate to some extent the reflexes on the vascular system," Professor Langley replied.
"WOULD PAIN CAUSE AN INCREASE OF BLOOD-PRESSURE?"
"IT WOULD CAUSE A RISE OF BLOOD-PRESSURE," replied the physiologist.
Of course, he insisted upon the sufficiency of the anaesthesia, but he
had made the most important admission which his evidence affords. IF
PAIN WERE FELT, IT WOULD CAUSE A RISE OF BLOOD-PRESSURE.