COPYRIGHT, 1913 By YALE UNIVERSITY PRESS First Printed May, 1913, 600 Copies...

In the year 1883 a legacy of eighty thousand dollars was left to the President and Fellows of Yale College in the city of New Haven, to be held in trust, as a gift from her children, in memory of their beloved and honored mother, Mrs. Hepsa Ely Silliman. On this foundation Yale College was requested and directed to establish an annual course of lectures designed to illustrate the presence and providence, the wisdom and goodness of God, as manifested in the natural and moral world. These were to

The lectures on irritability here published were held at the University of Yale in October, 1911. When the authorities of that University honored me by an invitation to give a course of Silliman memorial lectures, I accepted with the more pleasure as it furnished me with the opportunity of summarizing the results of numerous experimental researches carried out with the assistance of my co-workers during the course of more than two decades in the physiological laboratories of Jena, Göttingen and

Contents : Introductory. Earliest period. Francis Glisson as founder of the doctrine of irritability. Albrecht von Haller. The vitalists. Bordeu and Barthez . John Brown’s system. Johannes Müller and the specific energy of living substance. Rudolf Virchow’s doctrine of the irritability of the cell. Discovery of the inhibitory effects of stimulation. Weber , Schiff , Goltz , Setschenow , Sherrington . Claude Bernard studies on narcosis. Tropisms. Ehrenberg , Engelmann , Pfeffer , Strassburger , S

Contents : Principles of scientific knowledge and research. Origin and meaning of the conception of cause. Cause and condition. Criticism of the conception of cause. The conditional point of view. Conception of cause. The conditional point of view applied to the investigation of life. Conception of vital conditions. Definition of the conception of stimulation. The common problem of all scientific research is the investigation and formulation of natural laws. The assumption of a unity in the happ

Contents : The quality of the stimulus. Positive and negative alterations of the factors which act as vital conditions. Extent of the alteration in vital conditions or intensity of the stimulus. Threshold stimuli, sub-threshold, submaximal, maximal and supermaximal intensities of stimulus. Relations between the intensity of stimulus and the amount of response. The Weber and Fechner law. All or none law. Time relations of the course of the stimulus. Form of individual stimulus. Absolute and relat

Contents : Various examples of the effects of stimulation. Metabolism of rest and metabolism of stimulation. Metabolic equilibrium. Disturbances of equilibrium by stimuli. Quantitative and qualitative alterations of the metabolism of rest under the influence of stimuli. Excitation and depression. Specific energy of living substance. Qualitative alterations of the specific metabolism and their relations to pathology. Functional and cytoplastic stimuli. Relations of the cytoplastic effects of stim

Contents : Indicators for the investigation of the process of excitation. Latent period. The question of the existence of assimilatory excitations. Dissimilatory excitations. Excitations of the partial components of functional metabolism. Production of energy in the chemical splitting up processes. Oxydative and anoxydative disintegration. Theory of oxydative disintegration. Dependence of irritability on oxygen. Experiments on unicellular organisms, nerve centers and nerve fibers. Restitution af

Contents : Only processes of excitation are conducted, not processes of depression. Conduction of excitation in its two extreme instances. Conduction in undifferentiated pseudopod protoplasm of rhizopoda. Conduction of excitation with decrement of intensity and rapidity. Conduction of excitation in the nerve. Rapidity of conduction of excitation without decrement. Relation between irritability and conductivity. Conduction of excitation with decrement of the nerve after artificial depression of i

Contents : Conception of specific irritability. Alteration of specific irritability during and after excitation. Refractory period in various forms of living substance. Absolute and relative refractory period. Curve of irritability during refractory period. Dependence of the duration of the refractory period on the rapidity of the course of the metabolic processes in the living substance. Dependence on temperature. Dependence on supply of oxygen. Theory of refractory period. Refractory period as

Contents : Examples of effects of interference of stimuli in unicellular organisms. Interference of galvanic and thermic stimuli in Paramecia. Interference of galvanic and thermic stimuli and narcotics. Interference of galvanic and mechanical stimuli. Interference of galvanotaxis and thigmotaxis in Paramecia and hypotrii infusoria. Real or homotop interference, apparent or heterotop interference. The two effects of homotop interference of excitations: Summation and inhibition of excitations. The