1896.] The Circulation of Organic Matter. 157 



WEEKLY EVENING MEETING, 



Friday, April 24, 1896, 



Basil Wood Smith, Esq. F.E.A.S. F.S,A. Vice-President, 

 in the Chair. 



Professor G. V. Poore, M.D. F.R,C.P. 



The Circulation of Organic Matter. 



It is quite impossible to define " organic matter," or to indicate the 

 line, if there be any, between organic and inorganic. 



Organic matter is the material of which living things are made. 

 When a chemist analyses anything which is the product of life, 

 whether vegetable or animal, he often speaks of his incombustible 

 residue or ash as " inorganic matter," but this is clearly an arbitrary 

 use of the term, for this incombustible residue has formed an indis- 

 pensable part of one living thing, and may in due time be incorporated 

 with other living things as something which they cannot do without. 



It may well be that everything of which we have knowledge 

 (even including the igneous rocks) has at one time or another formed 

 part of a living organism, and it is certain that a large proportion of 

 the commoner chemical elements may form a part, more or less 

 indispensable, of the bodies and framework of plants or animals. 



Oxygen, hydrogen, nitrogen, carbon, chlorine, sulphur, phosphorus, 

 iron, sodium, potassium and calcium seem to be indispensable to 

 almost every living thing. Many more of the elements are constantly 

 found in some organisms, while others, such as lead, mercury, silver, 

 &c., may be temporarily incorporated with living bodies. 



We shall deal to-night mainly with those elements which are 

 pre-eminently mobile, which are constantly changing and exchanging, 

 combining and separating, and which are readily combustible. For 

 practical purposes one might indeed use the terms " organic " and 

 " combustible " to signify the same thing. 



With regard to solid matter, the power of readily circulating 

 implies a readiness of combustibility, but it must be remembered 

 that there is no hard line between combustible and incombustible. 

 This is a matter of temperature, and many things which are incom- 

 bustible here are said to be blazing in the sun. 



The combustion of organic matter may take place slowly or with 

 moderate rapidity, or with explosive violence. 



When we burn coal, which is a vegetable product, we find that 

 the carbon and hydrogen escape as carbonic acid and water, accom- 



