18 LIVERPOOL BIOLOGICAL SOCIETY. 
state of combination in the living matter, which he 
terms ‘‘ physiological units,” in order to account for vital 
phenomena.* It is true he attempts to restrict the 
function of these to the plastic powers of life, on which 
depend heredity and the development of individuals and 
species. But he is obliged to admit that those “ physio- 
logical units,’’ which are molecules one degree higher in 
complexity than those molecules of nitrogenous colloidal 
substance into which organic matter is resolvable must 
first form an aggregate able “‘to unite the nitrogenous 
molecules it meets with, into complex molecules like 
those of which it is composed” (vol. i., p. 11). That is 
to say, an aggregate possessing the faculty of combining 
heterogeneous compounds (pabulum) into matter like 
itself—growth, in fact—the very thing possessed by living 
matter and by no other substance in the world. Hence 
Herbert Spencer’s physiological units merely mean the 
peculiar state of combination of the elements funda- 
mentally essential to all living matter or protoplasm, 
although the latter may have, in addition, innumerable 
specific varieties with corresponding powers, derived from 
complex combinations of the units. 
The truth is, that the cardinal distinction between the 
action of living and non-living matter in a chemical point 
* If then, this organic polarity can be possessed neither by the chemical 
units nor the morphological units we must conceive it as possessed by certain 
intermediate units which we may term physiological. There seems no alter- 
native but to suppose that the chemical units combine into units immensely 
more complex than themselves, complex as they are; and that in each 
organism the physiological units produced by this further compounding of 
highly compound atoms haye a more or less distinctive character. We must 
conclude that in each case some slight difference of composition in these units, 
leading to some slight difference in their mutual play of forces, produces a 
difference in the form which the aggregate of them assumes.’-—Biology, 1884, 
Ley peek oes 
