time: the refreshing river 



The Giant Vista oj Evolution. 



Let us now take another look at the giant vista which has all along 

 been tlie background of our thoughts. The stage once prepared by 

 cosmic evolution for the appearance of life, what follows shows an 

 ever-rising level of organisation.^ The number of parts in the wholes 

 increases, as also the complexity of their structure and their inter- 

 relations, the centralisation and efficiency of the means of control 

 (whether humoral or neural) and the flexibility and versatility of 

 their actions on the external environment. The wholes become, 

 indeed, ever more independent of the external environment; by 

 regulation of exchanges in energy and materials an interior equilibrium 

 is doggedly maintained, and though death destroys it in the individual, 

 it continues in the species. If we run through any biological textbook,^ 

 we find abundant illustrations of this. Although some of the para- 

 crystals already mentioned show a degree of complexity which seems 

 to approach that of the simplest living organisms, it is the autotrophic 

 bacteria which first exhibit the basic phenomena of the new level, 

 reproduction and metabolism. They were (and are to-day) able to 

 synthesise all the carbon compounds needed for their architecture 

 from the carbon dioxide of the atmosphere by the aid of energy 

 obtained from oxidations of inorganic substances (iron, sulphur, etc.). 

 The many kinds of parasitic bacteria with which most of us are more 

 familiar are to be supposed a regression from these primitive forms. 

 But all was not regression, for by another big step cells grew enor- 

 mously larger and the protozoa came into being. Some of these 

 developed the photosynthetic mechanism, others did not. The former, 

 when united together in colonies, became the first plants, the latter, 

 similarly co-operating, became the first animals.^ Then began that 



^ This "preparation of the stage" presents problems of much interest, the classical 

 treatment of which is The Fitness of the Environment (New York, 1913), by Lawrence 

 J. Henderson. Consideration of the properties of water, carbon dioxide, ammonia, etc., 

 shows that if anything with properties at all akin to what we know as life was to develop, 

 it must needs have the properties it actually did have. This reciprocal fitness of the environ- 

 ment greatly strengtliens our view of the unity and continuity of the evolutionary process. 



^ For a student of another subject, an admirably philosophic introduction to biology 

 as a whole can be had in the freshly-written book of H. H. Newman, Outlines of General 

 Zoology (New York 1936). An excellent discussion of progress in evolution is given 

 by J. S. Huxley in his presidential address 10 the British Association, 1936, pp. 96 ff. 



^ The beginnings of social behaviour, if not of social organisation, can be seen already 

 in tlie aggregations of free-living protozoa (cf. H. S. Jennings, Behaviour of the Lower 

 Organisms, New York, 1906; The Beginnings of Social Behaviour in Unicellular Organ- 

 isms, Philadelphia, 1941; and in Science, 1941, 94, 447; also W. C. Allee, Animal 

 Aggregations, Chicago, 1931; Biol. Rev., 1934, 9, i; The Social Life of Animals, New 

 York, 1938). 



