vaughan: growth-rate of shoal-water corals 591 



The samples used were small cylinders, the surface layer of 

 which had been distorted by machining in the lathe. These 

 were annealed for periods of: 1, 2, 4, and 8 hours at 400°, 600°, 

 and 800°C. The data tabulated below for one series indicate 

 the general nature of the observations made and the results 

 obtained. 



The constancy of the thick ess of the reciystallized layer 

 (different for different temperatures) is very striking. Though 

 the crystals in this layer of recrystallized metal increase in size 

 upon annealing, there appears to be no appreciable increase in 

 thickness of the layer itself. The process is not a progressive 

 one from exterior inward, but begins simultaneously throughout 

 the layer which is capable of being affected at that temperature. 

 The results obtained are in support of, and in accordance with, 

 Tammann's theory of the recrystallization of ''cold-worked" 

 metals upon heating. 



GEOLOGY. — The geologic significance of the growth-rate of the 

 Floridian and Bahaman shoal-water corals.^ Thomas 

 Wayland Vaughan, Geological Survey. 



Except to allude to the continuation of the experiments and 

 observations, no specific report on the results of the study of the 

 growth rate of corals has been published since the one in Year 

 Book No. 10 of the Carnegie Institution of Washington, pages 

 148-156, Plates 4-6, where all data then available on the size 

 of year-old corals were presented. The technique for rearing 

 and planting corals and that for measuring corals growing under 

 natural conditions are described in the Year Book referred to 

 and in Year Book No. 9, pages 136-144, Plate 1. The descrip- 

 tions there given need not be repeated. 



As the object of the investigation should be made clear, it 

 should here be stated that stony corals are not suitable subjects 



1 Published by permission of the President of the Carnegie Institution of 

 Washington and of the Director of the U. S. Geological Survey. The field studies 

 were made under the auspices of the Department of Marine Biology of the Car- 

 negie Institution of Washington while the office facilities were furnished by the 

 U. S. Geological Survey. A fuller account of these investigations will appear 

 in the Year Book of the Carnegie Institution of Washington for 1915. 



