Yes growth is measureable.
Parameters for growth :
Growth is measured by a variety of parameters some of which are increase in fresh weight, dry weight, length, area, volume cell and growth in number of cells. For example
Growth by increase in the number of the cells : Maize root apical meristem can give rise to more than 17, 500 new cells per hour.
Growth in size : Cells of watermelon may increase in size by upto 3,50,000 times.
Growth in length : Growth of pollen tube is measured in terms of its length.
Growth in surface area : An increase in surface area denotes the growth in a dorsiventral leaf.
Auxins are of two types :
(1) Natural auxins : These are naturally occuring auxins, isolated from plants and are regarded as phytohormones e.g. IAA. NAA etc.
(2) Synthetic auxins : These are synthesized by artificially e.g. IBA 2,4-D etc.
Auxin was isolated by F.W. Went from tips of coleoptiles of oat seedling.