Major Problems in Developmental Biology

The first symposium on Development and Growth was held in August 1939 (Fig. 1 ) . S i x years before, in 1933, Thomas Hunt Morgan, in his earlier years an experimental embryologist, was awarded the Nobel Prize for his discoveries concerning the function of chromosomes in the transmission of heredity; four years before the first symposium, in 1935, Hans Spemann had received the prize for his discovery of the organizer effect in embryonic development. Yet Pontecorvo, i n his introduction to "Trends in Genetic Analysis," has stated that: "It is no exaggeration to say that before about 1940 what was known on the nature and mode of genetic specificity—i.e., what was known about chromosomal heredity —was but a series of developments on the theory of the gene" (Pontecorvo, 1958, p. 2 ) . Richard Goldschmidt wrote in the preface to his "Physiological Genetics" in 1938 that: "It is emphasized over and over again by writers of texts and by general speakers [that] we know next to nothing of the action of the hereditary material in controlling development" (Goldschmidt, 1938, p. v ).