x Obituary Notices of Fellows deceased. 



movements, among these being that of a recording stethometer for measuring- 

 the movements of the chest wall, the instrument being designed by himself 

 for this purpose. 



Probably his earliest strictly physiological inquiry of an experimental 

 kind was that carried out for the Eoyal Medico-Chirurgical Society in 1862' 

 and 1863 as to the best methods for the resuscitation of the apparently 

 drowned ; these investigations led to the adoption in 1864 of the Sylvester 

 method by the Eoyal Humane Society. Having started on this purely 

 physiological investigation, he was led on to others, and worked upon the 

 respiratory and circulatory mechanisms of mammals for several years prior 

 to his being appointed to the Physiological Professorship at University- 

 College. 



In 1867 he was elected a Fellow of the Eoyal Society, mainly for the 

 importance of his researches into subjects connected with public health, but 

 the value of his physiological investigations was also recognised, for in this, 

 year he was selected by the Council of the Society to give the Croonian 

 Lecture, the subject being " The influence exercised by the Movements of 

 Eespiration on the Circulation of the Blood." In 1872, in conjunction with 

 Poster, Lauder Brunton and Klein, he published the ' Handbook of the 

 Physiological Laboratory,' the special parts for which he was responsible 

 being those devoted to experimental investigations on the circulation and 

 on respiration. 



His conception of physiology, as one prominent aspect of general biology,. 

 led him gradually into more recondite paths, and he began to devote his 

 energies to the investigation of certain fundamental or elementary aspects 

 of living processes. The nature of these aspects is set forth in the 

 remarkable address which he delivered in 1893 at Nottingham, as President 

 of the British Association. The rule of action of all such processes is there- 

 conceived to be " in each instance the interest of the organism as a whole 

 of which it forms part, and the exciting cause some influence outside of the 

 excited structure, technically called a stimulus." 



In 1872 he apppears to have commenced a series of experiments into the 

 conditions which determine that universally distributed phase of living 

 tissues termed excitability, and, with his characteristic craving for exact 

 knowledge, he associated with this series the experimental determination of 

 the precise history of an active process from the point of view of its time- 

 relations. This involved the accurate measurement of the time occupied 

 by the development, maintenance and subsidence of that excitatory change 

 or state which a living tissue displays in response to an effectual stimulus. 

 The time relations of such excitatory responses are undoubtedly largely 

 dependent upon the character of the active change, and, when this is an 

 alteration in mechanical form or a development of heat, all methods of 

 recording are more or less vitiated by the circumstance that the instrument 

 employed for recording the change has its own personal time; moreover,, 

 even as regards the actual tissue, all observed changes of this character are 



