“…This was clearly recognized in ontogenetic studies of wheat and Sudan grass by Ballard and Petrie (1936) and Petrie (1937), of oats by Williams (1936Williams ( , 1938Williams ( , 1948, of tobacco by Petrie, Watson, and Ward (1939), Watson and Petrie (1940), and Petrie and Arthur (1943), of flax by Tiver (1942), and of linseed by Tiver and Williams (1943). More recently, studies on similar lines have been made for barley and rye by Williams and Shapter (1955) and for the tomato plant by Gates (1955aGates ( , 1955bGates ( , 1957. Common features of all these studies are adequate sampling on from five to ten occasions during growth, the separation of the plants at least into their major parts, and the analysis of growth in terms of dry weight change.…”