8 = PRESIDENT’S ADDRESS. 
tion.® These, surely, it may be thought, are not shared by matter which 
is not endowed with life. Unfortunately for this argument, similar 
processes occur characteristically in situations which no one would 
think of associating with the presence of life. A striking example of 
this is afforded by the osmotic phenomena presented by solutions 
separated from one another by semipermeable films, a condition pre- 
cisely similar to that which is constantly found in living matter.? 
It is not so long ago that the chemistry of organic matter was 
thought to be entirely.different from that of inorganic substances. But 
the line between inorganic and organic chemistry, which 
Chemical up to the middle of the last century appeared sharp, 
Spore subsequently became misty and has now disappeared. 
ing life. Similarly the chemistry of living organisms, which is now 
a recognised branch of organic chemistry, but used to be 
considered as so much outside the domain of the chemist that it could 
only be dealt with by those whose special business it was to study 
‘vital’ processes, is passing every day more out of the hands of the 
biologist and into those of the pure chemist. 
Somewhat more than half a century ago Thomas Graham published 
his epoch-making observations relating to the properties of matter in 
the colloidal state: observations which are proving all- 
ae important in assisting our comprehension of the properties 
of living of living substance. For it is becoming every day more 
matter. 
Identity of  2PParent that the chemistry and physics of the living 
physical and Organism are essentially the chemistry and physics of 
chemical = nitrogenous colloids: Living substance or protoplasm 
processes in 
living and always, in fact, takes the form of a colloidal solution. 
non-living = In this solution the colloids are associated with crystalloids 
mse (electrolytes), which are either free in the solution or 
attached to the molecules of fhe colloids. Surrounding and enclosing 
the living substance thus constituted of both colloid and crystalloid 
material is a film, probably also formed of colloid, but which may 
have a lipoid substratum associated with it (Overton). This film 
serves the purpose of an osmotic membrane, permitting of exchanges 
by diffusion between the colloidal solution constituting the protoplasm 
* The terms ‘assimilation’ and ‘ disassimilation’ express the physical and 
chemical changes which occur within ‘protoplasm as the result of the intake of 
nutrient material from the circumambient medium and its ultimate transforma- 
tion into waste products which are passed out again into that medium; the whole 
cycle of these changes being embraced under the term ‘ metabolism.’ 
* Leduc (The Mechanism of Life, English translation by W. Deane Butcher, 
1911) has given many illustrations of this statement. In the Report of the 
meeting of 1867 in Dundee is a paper by Dr. J. D. Heaton (On Simulations of 
Vegetable Growths by Mineral Substances) dealing with the same class of 
phenomena. See also J. Hall Edwards, Address to the Birmingham and Mid- 
land Inst., Nov., 1911. The conditions of osmosis in cells have been especially 
studied by Hamburger (Osmotischer Druck und Ionenlehre, Wiesbaden, 1902-4). 
