View source for Reference growth axis

"'''The reference growth axis''' describes current direction of growth of the shell. Actually, the reference growth axis has no direct morphogenetic representation during formation of a chamber. This axis resembles the fixed "axis of coiling" sensu Raup (1966) or Signes et al. (1993) because both of them serve as reference lines for certain transformations. The difference is that our growth axis is not fixed, but moves with formation of successive chambers." (from [[Tyszka & Topa 2005]])