THE PRINCIPLES OF BIOLOGY. 
35 
THE PRINCIPLES OF BIOLOGY.* 
Exposition of Chapter I. Organic Matter. 
By Alfred Hill, M.D., F.I.C. 
Organic Matter . 
Of tlie four chief chemical elements of living bodies, three 
are gaseous, viz., oxygen, hydrogen, and nitrogen, and one 
is solid, viz., carbon. Until recently these gaseous elements 
had resisted all attempts to reduce them to the liquid form, 
and their great mobility has a significant bearing on the 
redistributions of matter constituting evolution. 
The compounds produced by the union of these elements 
have physical properties which are resultants , in which the 
properties of the elements are still in action, though mutually 
obscured, so that the molecular mobility of the various 
compounds is influenced by the molecular mobility of its 
constituents. 
Chemically the affinities of hydrogen, carbon, and nitrogen 
are of narrow range and low intensity; this chemical 
indifference is most marked in the case of nitrogen. 
Allotropism, or the faculty of elementary bodies to assume 
different physical states, is well seen in the organic elements ; 
while isomerism, the analogue of allotropism, is exhibited in 
the compounds. This is strikingly true, not only of carbon 
and oxygen, but also of sulphur, phosphorus, silicon, silica, 
and even of iron, which latter are essential constituents of 
organic bodies, although their relative quantity be not large. 
The four principal organic elements present extreme 
antitheses—chemical, between oxygen and nitrogen; physical, 
between carbon and the three gases. By these contrasts 
of properties differentiation and integration are facilitated, for 
while unlike units are most -easily separated, they are also 
most easily segregated. 
The binary compounds of these four elements have less 
molecular mobility than the elements themselves, while it is 
greater than that of binary compounds in general; chemically 
* It is intended to give, under tlie above heading, from time to time, 
short abstracts of the addresses or expositions of the portions of 
Mr. Herbert Spencer’s works now under consideration by the Members 
of the Sociological Section of the Birmingham Natural History and 
Microscopical Society. By this means a continuous record of the 
transactions of the Section will be preserved, and it is hoped that the 
attention of other Naturalists may be directed to Mr. Herbert Spencer’s 
writings, in this somewhat popular form. Where illustrations are 
given these will be mentioned also. 
