SECTION I.— PHYSIOLOGY. 



FUNCTION AND DESIGN, 



ADDRESS BY 



PROFESSOR J. B. LEATHES, F.R.S., 



PRESIDENT OF THE SECTION. 



Among natural sciences physiology takes a place which in one respect is 

 different from that taken by any other. It studies the phenomena of life, 

 but more particularly the ways in which these phenomena are related to 

 the maintenance of life. Anatomy and morphology are concerned with 

 the forms of living organisms and their structure ; biological chemistry, 

 as distinct from physiology, with the composition of the material in which 

 the phenomena of life are exhibited. The province of physiology, in 

 studying the functions of these forms and of this material, is to ascertain 

 the contributions that they make to the organisation of the living 

 mechanism, and learn how they minister to the maintenance of its life. 

 Function implies ministration, structure for physiology implies adaptation 

 to function, what in a word may be termed design. 



Ultimate analysis of the phenomena with which physiology deals leads 

 to the fundamental distinction between matter in which life is manifested 

 and matter in which it is not. Life is exhibited only in aqueous systems, 

 containing unstable, perishable combinations of carbon with hydrogen, 

 nitrogen, sulphur, phosphorus and oxygen, in the presence of certain 

 inorganic ions, those which are present in the sea, the native environment 

 originally of all forms of life ; and the inalienable property that such 

 matter exhibits when alive, and that matter which is not alive does not, 

 is that these unstable organic combinations are for ever reforming them- 

 selves out of simpler combinations that do not exhibit this property, and 

 do so at a rate which averages at least not less than that at which they 

 break down. This power of self-reformation, spontaneous regeneration, 

 operates not only when living organisms, cells or communities of cells are 

 growing or reproducing their kind ; the very maintenance of living 

 existence requires by definition that it should persist. In the absence of 

 water the living process may sometimes apparently be suspended for a 

 time, as it may be if the surrounding watery medium is immobilised by 

 cold : it is a question whether this is anything more than a retardation 

 to a rate of change that is imperceptible by the ordinary methods of 

 observation, and a question how long such suspended animation is possible 

 where it is possible at all. It is only where water has the kinetic activity 

 of the liquid state that spontaneous regeneration of living matter can in 

 general proceed, and then it must, for when it ceases the unstable material 

 ceases to live. 



Chemical analogies for this power of spontaneous regeneration, if such 

 exist, can only exist in part ; in the present state of our comprehension 



