Further Observations on Scale Formation in Chrysochromulina Chiton

Abstract

The normal form of the species has been compared with a deviant form and the processes of scale production in both more fully studied. The deviation is shown to be genetically based, possibly a mutation, of which the main structural expression is loss of capacity to develop the normal outer layer of material on each scale. The large scales also lack rims, a flange on the back giving a spurious resemblance to an inverted rim. A significant factor in determining orientation of the large scales appears to be a deposit of amorphous material on the morphologically outer side, which though much reduced in the deviant strain is still present. Orientation of scales in both strains of the species is therefore basically identical and independent of overall shape, though it is structurally determined before liberation from the parent Golgi cisternae. Changes in the latter have been traced up to and including the act of liberation of the contents to the exterior. This takes place near to the flagellar bases and there are some indications that participation by endoplasmic reticulum may be involved.