ON CORALLITES APPARENT IN X-RADIOGRAPHS OF SKELETAL SLICES OF PORITES

X-radiographs of slices cut from massive skeletons of Porites appeared to show more corallites than are present on the slices. The ratio of apparent:real corallites averaged 1.21+/-0.09 in slices cut from 25 colonies of Porites. This phenomenon was tested by computer-simulated X-radiography of a ''slice of skeleton'' made up of perfectly packed hexagons. The hexagons simulated corallites. The ''slice'' was ''X-radiographed'' at different angles and resulting ''density'' profiles were averaged. The main contribution to the average profile came from zigzag arrangements of walls within the hexagonal pattern. This arrangement combined with occasional end-to-end arrangements of walls to give a frequency of density peaks slightly higher than the frequency of hexagons. This model is presented as a plausible explanation for the number of corallites apparently seen in X-radiographs.