XII 



PREFACE 



process, leaving it for the future to curry further the reduction to simpler 

 laws. Nevertheless, I fear that I may in some cases have been unable to 

 resist the temptation to suggest hypotheses, even where the experimental 

 data are inadequate. May I venture to hope that some of these suggestions 

 will help to indicate gaps and to excite research to fill them up ? If so, any 

 labour involved in the writing of this book will be amply repaid. 



It should be unnecessary to point out that vital processes can only )>e 

 investigated where they exist, that is, in the living organism, either as a 

 whole or in its separate parts, when these can be prepared in such a way as 

 not to interfere with their function, or, if so, only in a known manner. 

 Such experiments, when vertebrate animals are concerned, are known 

 sometimes as " vivisections," an objectionable and misleading name. 1 should 

 not have thought it necessary to refer to this question, were it not that 

 certain people, whom one might reasonably expect to possess better know- 

 ledge, appear to hold that the progress of physiological science is possible 

 without such experiments. Vesalius stated that the simplest experiment 

 on the living animal, as a rule, revealed more than a long study on the dead 

 body. With another set of people, who see no value in physiology, and 

 frequently also none in science of any kind, I have naturally no concern, 

 except to remind them that a great artist like Leonardo da Vinci, whom 

 they probably hold in some esteem, not only thought differently, but 

 actually performed " vivisections." 



Finally, nowhere is the admonition of St Paul to the Thessalonians 

 (Hrst epistle, chap, v., 21), which I have placed on my title-page, more 

 necessary than in physiological work, " prove " (or rather " test ") " all 

 things, hold fast that which is good." Let me remind the reader, also, that 

 the word translated " good " is KuAos, which also means " beautiful," and in 

 the passage quoted implies " true." Let us try to imitate the ancient 

 Greeks, and look upon all that is true as both beautiful and good. All 

 science should be KaA?;, and not, as to many narrow minds, essentially ugly, 

 although possibly necessary. It is not always easy, however, to take this 

 pi int of view. But some of the greatest artists of the past devoted much 

 time to scientific investigations ; Leonardo has been mentioned already, and 

 Christopher "Wren may be added. 



With regard to the use of the word "good" as applied to experiments, 

 the remarks of Claude Bernard (1875, p. 516) should be kept in mind by 

 the physiological investigator : " In physiology, more than anywhere else, 

 on account of the complexity of the subjects of experiment, it is easier to 

 nuike bad experiments than to be certain what are good experiments, 

 that is to say, comparable. This is the reason of the contradictions so 

 frequent amongst experimenters, and it is one of the chief obstacles to 

 the advancement of medicine and of experimental physiology." 



W. M. BAYLISS. 



UNIVERSITY COLLEGE, LONDON, 

 1914. 



NOTE. I may take the opportunity here to thank those authors and publishers who have 

 kindly allowed the reproduction of certain illustrations. Those to which no name is attached 

 are by myself and, for the most part, were prepared especially for this work. 



