INTRODUCTION :
THE VALIDITY OF EXPERIMENTAL RESULTS IN THE INTERPRETATION OF CARDIAC AFFECTIONSThe experimental investigator who, within the span of at most a few hours, seeks to reproduce in animals the cardiac affections which Nature pleases to produce in man in a slow and gradual fashion, runs the risk of bringing about conditions which may not be comparable to those actually existing in diseased individuals. Thus, the sudden tearing of a valve may produce a reaction in experimental animals that is more serious than a similar insufficiency, the gradual development of which is accompanied by compensatory phenomena. It becomes a part of the experimental problem, therefore, not only to elucidate the dynamic effects of a certain pathological change, but also to determine, as completely as possible, the influence that secondary accompaniments to such a condition have on the primary affection.Moreover, the hearts of animals on which experimental work