1. The more general and systematic study and teaching of anatomy, human and comparative, has naturally added materially to our knowledge of the circulatory system, aided by careful dissections and coloured injections of vessels, which the development of the microscope has enabled observers to trace, even to their minutest terminations. In this way much has been revealed with regard to anatomical details, especially in relation to the circulation in particular organs and structures. Of course, to the microscope we are also entirely indebted for our knowledge of the normal histology of the heart and vessels, as well as of the formed blood-elements; and of important points connected with the circulation of the blood in the vessels. It may further be noted, that the application of many advances in physics and chemistry to the study of the circulation and the blood, has contributed in large measure to the establishment of numerous physiological facts of essential value, with which we are now quite familiar.
2. Observations and investigations directed to the heart and vessels, on simple and harmless lines, to which no one could possibly object, have contributed in no small degree to the progress of knowledge with regard to these structures, as well as to the circulation of the blood, both from a physiological and clinical point of view. Thus the mere study of the cardiac movements and arterial pulse, under
