In response to numerous requests I have brought together into this volume eight papers which may serve as a supplement to the volumes previously published and as a preface to monographs now in preparation.

In the first of these addresses, the Ether Day Address, delivered at the Massachusetts General Hospital in October, 1910, I first enunciated the Kinetic Theory of Shock, the key to which was found in laboratory researches and in a study of Darwin's "Expression of the Emotions in Man and in Animals," whereby the phylogenetic origin of the emotions was made manifest and the pathologic identity of surgical and emotional shock was established.

Since 1910 my associates and I have continued our researches through:

(a) Histologic studies of all the organs and tissues of the body;

(b) Estimation of the H-ion concentration of the blood in the emotions of anger and fear and after the application of many other forms of stimuli;

(c) Functional tests of the adrenals, and

(d) Clinical observations.