SCIENCE AND LIFE

Press, Volume LXX, Issue 21118, 20 March 1934, Page 13

SCIENCE AND LIFE

EVOLUTION OLD AND NEW ADDRESS 15Y PROFESSOR E. I'LRCIVAL "Man's attention has now for a long time been directed towards the origin of life,"' said Professor E. Pcrcival in his lecture, "Evolution, Old and New," delivered at Canterbury College last night. Outlining the history of man's investigation in such matters he explained the two old theories of spontaneous and gradual generation. The former originating in Mesopotamia was known as the Mosaic theory, and had had a profound effect on thought up to comparatively recent, times, while in Greek times it had been favoured by Aristotle. The latter that believed all things tended to improve gradually owing to the urge to develop the bes* within them. Eighteenth Century Work A Swedish scientist proposed, somewhat in accordance with the Mosaic theory, that special types had been created spontaneously in the beginning, as for example the dog family, from which developed the wolf and the domestic animal. In France several men were engaged in investigation of the origin of life, and further support to this theory was afforded by Cuvier, whose work on fossils had led him to state that generation took the form of spontaneous ropopulation on areas of the earth's surface where natural development had extinguished life. Another Frenchman who had done early work in the classification of types, observed, as did others, that there was a tendency for types to merge. This was Lamarck, who noted the adaptation of the skeletal body to environment and suggested that the organs were built up or degenerated according to their use in life. The characteristics so acquired became hereditary.

The IMudern Aspect The relationship between animal structure and environment led to the suggestion by Buff on that characters created by environment were inherited, but nearer our own times was Erasmus Darwin, who. influenced by Burton, favoured this theory. He contributed the idea that nil life had a common source, thus making a breakaway from the Mosaic tradition of separate species in the original creation. It was he who made a new move in regard to the age of the world, the origin of which lie placed at not merely 4000-5000 8.C., but a figure infinitely greater. The desire for classification of organic structures played a very important part in the establishment of modern knowledge, one of the earliest workers in this direction being Lamarck.

Natural Slection I Charles Darwin advanced the thin ! new theory of "naiural selection,"] which meant, briefly, the selection i from others of variations which were; useful. The means of passing on these ! variations remained a mystery, but a suggestion was that organisms passed , from each organ through the blood stream to the germ cells, thereby conveying the new characteristics. The studies of von Baer in the j embryo chick, dogfish, and lower forms of life led to ins expressing the; "biogenetic theory." which stated. \ briefly, that (no life-history of the' organism recapitulated its ancestry in | the progeny. ! But the really hit advance was j made by Pasteur, who cie<;royed the' theory of ipontar.oous creation by! proving that infoetun by bacteria 1 from without had causer] seeminriv ! automatic generation of life. Hn- work I was the foundation of a large branch | of modern medical science. I Up to tile time of Darwin and his: protagonists it was held that environ- j ment had a direct effect on the j character of the organism, but the j proof by V/eismann that the germ- ] plasm was almost completely scpar-, aled from environment exploded the,

theory. Recent experiment confirmed this. Mendel Work done by an Austrian monk in experimenting with seeds led to the discovery of an important fact which had remained practically unnoticed for many years. It was found that enly a definite number of forms could be obtained by the introduction of variations from other stock and from these the original could be produced l;y judicious breeding. "'Mutation" vrai the term applied to this process whereby new forms could be obtained suddenly without any break, as opposed to the gradual fluctuation. Lantern slides were used to illustrate gradual development in animal forms, one series tracing the life-his-tory of the elephant from its home in Egypt to Africa and India, as it lived tc-day. Next week Dr. O. H. Frankel will continue on these lines in a lecture, "Variation and Inheritance."