Development is the progressive attainment of full-grown com plexity from comparatively undifferentiated simplicity, whether that be in stump or fragment, in leaf or bud, in spore-cell or germ-cell. It implies an expression of hereditary initiatives in appropriate nurture, and often in such a way that the individual stages in the ontogeny can be correlated with great steps in the racial history or phylogeny. Development, with its central fact of progressive differentiation and integration, is particularly to be thought of in connection with the building up of the embryo, but it cannot be separated from the everyday repair of worn-out tissue, the replacement of periodically deciduous structures (like leaves and hair), and the frequent regeneration (q.v.) of lost parts, thus linking back with reproduction and growth.
(c) In the third place living creatures stand apart from non living things in their purposive behaviour, in their power of en registering experience, and in their capacity for giving rise to the new—a third triad. Many non-living things, such as explosives, react forcefully to outside stimulus, but organisms are marked by the self-preservative efficiency of their reactions. Only the higher big-brained animals can be credited with perceptual pur pose, but the quality of purposiveness seems to be co-extensive with life. The organism is an agent that gets things done, at various levels of behaviour—intelligent, instinctive, tropistic, re flex, and so forth. The mental aspect may in many cases be sub ordinated to the bodily, but in the majority there is the bent bow of endeavour, even though the creature's awareness of that en deavour may be dim. The mental aspect seems to be struggling for expression throughout, and the organism appears as a psycho physical being, now (mind)-BODY and again (body)-MIND (see BIOLOGY).
A bar of iron is never quite the same after it has been severely jarred; a violin suffers from mishandling. But these are hardly more than vague analogies of the distinctive power that living creatures have of enregistering the results of their experience, of establishing internal rhythms, of forming ...onditioned reflexes and habits, and of remembering. Individual experience is built into the individual organism and influences subsequent reactions.
Finally, it must be recognized as characteristic of organisms that they give origin to what is new; they have evolved in the past, and the evolution of many is still going on. Variability and evolvability must be ranked as fundamental characteristics of living beings. The organism selects stimuli from its environment and often moves from one environment to another ; the organism is often experimental, moulding itself by its efforts; it tests the newness of its inheritance in its ceaseless trafficking with circum stances. The central secret of life is missed if the organism is not recognized as in some measure a struggling sub-personality.
To sum up, the characteristics of organisms are :—(a) Per sistence of integrity amid ceaseless change, there being (I) a self-preservative compensation of down-breaking by up-building, (2) a metabolism of proteins and other complex substances in a colloidal state, (3) a chemical individuality; (b) a triad of linked capacities, namely, (4) growth, (5) multiplication, (6) develop ment; and (c) the crowning triad of (7) effective behaviour, (8) enregistration of experience, (9) evolvability.
gested that since an organism without its everyday functions is rather an empty abstraction, the term function in the 0---tf--w: o formula, should rather read "functionings," i.e., the work or on-goings, the actions and reactions of the organism as a whole. The Drama of Life.—What has been said gives too cold an impression of life, which must be envisaged as a drama on a crowded stage. (I) Whatever the secret of vital activity may be, it must be thought of as an overflowing spring. Organisms accu mulate energy acceleratively and must multiply. Life is like a river that is often in flood. (2) From the ant-hill, the bee-hive, the rookery, the rabbit warren, there comes the impression of urge and endeavour. Whether the urge be vegetative, appetitive, tropistic, instinctive or intelligent, organisms are almost always after something—never satisfied. The more they get the more they want. (3) But the quality of life rises to what may be called insurgence. Animals in particular are full of daring and adven ture. As Goethe said, they are always attempting the next to the impossible and achieving it. This is well illustrated by gossamer spiders making aerial journeys, or by Arctic terns within the Antarctic Circle; but it finds many an unsensational expression. (4) Another quality, so universal that it must be called character istic, is adaptiveness. Practically every organism is a bundle of adaptations or fitnesses. As Weismann said, "If all the adapta, tions are taken away from a whale, what is there left ?" (5) It is perhaps an expression of this adaptiveness that so many living organisms form linkages with others. There is no aloofness in the realm of organisms; nothing lives or dies to itself. Thus animate nature is characteristically a system,—a fabric that changes in pattern and yet endures. Though the individual threads of the web are always dying, they are replaced without a discontinuity. There is wear, but no except when man carelessly interferes with the loom, or when some physical violence, like flood or fire, causes an inevitable rent. (6) But this leads to another characteristic of the biosphere that marks it off from the cosmosphere : there is continual sifting. A new star often appears in the sky, but there is no indication of any struggle for existence or selection of the relatively more fit. But who can describe the advancement of life and leave out winnowing? There is cosmic flux and there is organic flux, but only in the latter is there discriminate elimination.
(7) Another characteristic of living creatures is their beauty. All independently-living organisms are artistic unities, with pro tean wealth of beauty in form and colour, in pose and movement, expressing a harmonious life from which the discordant has been more or less completely eliminated. Apart from exceptions, like parasites, which prove the rule, organisms are like works of art.
(8) Nothing can be said as to the mental aspect of a wood anemone and only a little about that of a sea-anemone, but a pic ture of life must include the fact that in organisms there is the promise and potency—and in higher animals the epiphany—of "Mind." Perceptual inference is a relatively late achievement ; conceptual inference or reason is man's prerogative; but through out the animal kingdom there is a stream of inner life, of feeling and purpose, even when there is not very much in the way of intelligence. The probability is that "Life" and "Mind" are co extensive. (9) But the crowning characteristic of life is its pro gressiveness. No doubt there have been eddies and stagnant pools, but on the whole there has been a flow in the stream of life, and it has been uphill! As epoch has succeeded epoch for inconceiv ably long ages, life has been slowly creeping—sometimes swiftly leaping—upwards, towards greater fullness and freedom. The whole process must be envisaged in the light of its outcome, organic evolution in the light of man.