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 co lonies of Porites. This phenomenon was tested by computer-simulated X- radiography of a ''slice of skeleton'' made up of perfectly packed hex agons. The hexagons simulated corallites. The ''slice'' was ''X-radiog raphed'' at different angles and resulting ''density'' profiles were a veraged. 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 fr equency of density peaks slightly higher than the frequency of hexagon s. This model is presented as a plausible explanation for the number o f corallites apparently seen in X-radiographs.