1898] MR HERBERT SPENCERS BIOLOGY 381 
failure of the controversialists to distinguish carefully between 
noumenal and phenomenal causation. 
The question may now be asked whether Mr Spencer is well- 
advised in attempting to comprise under one definition of life (1) 
certain fundamental attributes of living matter and (2) sundry com- 
plex results of evolution. Is not the correspondence between life 
and its circumstances rather the result of the interaction of vital 
factors, under the influence of the environment, than a primary 
characteristic of the vital factor itself? And if it be true that the 
degree of life varies as the degree of correspondence (which is open 
to question, since it is rather struggle than attainment which calls 
forth most strenuous vital energy) it is surely aggregate results, 
rather than fundamental properties, that we have in mind. If a 
unit must be selected, the cell, not the metazoon or analogous 
plant-complex, seems to be the more appropriate. But it is per- 
haps more profitable to fix attention, not on the variable unit, but 
on the common substance—protoplasm ; to say that protoplasm has 
certain specified metabolic or other properties, that the. processes 
carried on in virtue of these properties are what we comprise under 
the term life, and that evolution is the outcome under certain given 
conditions. 
If Mr Spencer reply that the outcome in evolution is itself a 
fundamental attribute of life, it is difficult to see, in view of his 
position with regard to the dynamic element, on what @ priori 
ground he criticises the hypothesis of determinate evolution—the 
orthogenesis of Eimer. To argue that the evidence of such de- 
terminate evolution is insufficient is a perfectly legitimate scientific 
position. But Mr Spencer goes further. He says: “The assertion 
that evolution takes definitely-directed lines is accompanied by no 
indication of the reasons why particular lines are followed rather 
than others. In short, we are simply taken a step back, and for 
further interpretation referred to a cause said to be adequate but 
the operations of which we are to imagine as best we may.’ Ii, 
however, we are to believe in a dynamic element .in life, itself 
inexplicable, and if the outcome in evolution is in itself a funda- 
mental attribute of life, it is difficult to see why the inexplicable 
determinate tendency should not be part and parcel of the in- 
explicable operation of the dynamic element. But if we regard 
evolution as the result of the complex interaction of vital factors, 
then we may fairly demand an explanation of the manner in which 
such interaction can give rise to orthogenesis. 
It would be unprofitable (even if space permitted) to discuss at 
any length the pros and cons of what Mr Spencer terms direct 
equilibration. He is deeply committed to the inheritance of ac- 
quired modifications, and on this hinges much of his interpretation, 
