--------------------- There are some simple and painless experiments which may be demonstrated to any set of pupils, although living animals are the subjects of them. The demonstration of the circulation through the web of the frog; the demonstration of the different natural temperatures of the bodies of animals, including man; the influence of various anaesthetic vapours; the collection of the breath of various animals for the purpose of analysis,--these are all free from objection.... In a word, all experiments which are painless and harmless, are, as I assume the most humane would admit, free from any charge of error. But when we come to consider the application of experiment of a severe kind as a means of education of pupils who are making a study of physiological problems, there is a reason for hesitation. In my student days, such an experiment was never dreamed of. The professor of physiology would relate the facts derived from experiment, on which some important theories were founded; he would, for instance, explain what experiments were made by Harvey in order to describe the circulation of the blood, but he would not attempt to repeat those experiments in the lecture-room. He would describe, in his remarks on the functions of the nervous system, the researches of Sir Charles Bell, ... but he would never think of repeating Bell's experiment of division of the nerves in the column, alleging forcibly Bell's own objection to its repetition. It was the same on every point. He would relate the theory; relate the pros and cons; relate possibly his own independent inquiries, or what he had seen experimentally performed by other independent investigators; but with that explanation, he would be content. --------------------- When I was teaching physiology as I did teach it in a medical school for many years, I abstained for a long period from the direct experimental method. I found no difficulty, and my classes worked satisfactorily. The students had the credit of becoming good physiologists, and I am sure there was nothing shirked. In the latter part of my time, I followed occasionally the plan of making a few experiments in the way of demonstration; and although these were rendered painless, the innovation was not the success that was expected.... Intellectually, I do not think my classes were assisted, in the main, by the experimental demonstration. I am sure it limited my sphere of usefulness, by leading me, in the limited time at my command, to omit some parts of physiology of a simpler, less controversial, and more useful kind. I am bound to say that, morally, I do not recall the effect as producing all that could be wished.... I gave up experiments in my classes, not from any sentiment, but BECAUSE I GOT ON BETTER WITHOUT THEM. I did not omit the facts derived from experiment, I did not omit the report of my own experimental