902 LIFE : OUTLINES OF GENERAL BIOLOGY 



of the Royal Hunt, who had no duties save signing his name twice 

 a year. It would be an anachronism to suppose that there are no 

 anachronisms in our midst to-day. 



It would be of high value to make an index expurgatorius of 

 anachronistic forms of speech, that confuse issues and dull clear 

 thinking. We mean mischievous anachronisms, such as the withering 

 retort when an uncomfortable puncturing fact is adduced — "Oh, but 

 that's the exception that proves the rule.'' But even worse than 

 forms of speech that have drifted from their old moorings are 

 anachronisms of thought and action. Thus indiscriminate alms- 

 giving and dysgenic parentage are anachronisms of conduct; and 

 anti-evolutionist argument is an anachronism of thought. But 

 saddest of all in personal experience is the first glimpse one gets of 

 the fact that one has oneself become an anachronism ! 



RETROSPECT: THE CHANGING WORLD-ENVIRONMENT. 



— In our short human lifetimes, and even within the history of 

 our after all very recent science, the world-environment of life 

 seems broadly stable. But with that longer view of the cosmic past, 

 and of its varied scenes of life, which geology and palaeontology have 

 given us, we cannot too clearly keep before our minds the vast 

 changes of the environment of life which have been and still are 

 in progress. Notably, for instance, those of the composition of 

 the atmosphere since earliest times. Thus note first the perpetual 

 reduction of the carbon dioxide of the atmosphere, and this not 

 simply by plant life as preserved in coal, etc., but also by the vast 

 accumulation in many strata of the hard parts of animals. Note 

 again the corresponding increase of the oxygen of the atmosphere, 

 for, as Kelvin pointed out many years ago, the bulk of the oxygen 

 of the atmosphere must have been substantially fixed through the 

 oxidation of the earth's crust before and during its consohdation, 

 so that the present high proportion of 21 per cent, must have sub- 

 stantially accumulated from the photosynthetic activity of green 

 plants throughout their history. But if these two processes of atmo- 

 spheric change be admitted as in progress throughout evolutionary 

 history, must not our general retrospect of evolution in its physio- 

 logical terms give a very considerable importance to this increase 

 of oxygen, with its ever-intensifying respiratory stimulus to the 

 activities of life? And correspondingly, in the decrease of CO^, 

 must we not see a concurrent factor towards their activation also? 

 That for the Carboniferous flora the atmosphere must have been 

 substantially richer in CO2 than now, has often been pointed out 

 as a condition favourable to its exuberance: and conversely, 

 throughout this ever-continuing impoverishment of the atmosphere 

 for vegetation, we cannot but recognise the advantage of all manner 

 of variations favourable to photosjmthetic efficiency, in which the 



