LIMIT OF CORAL GROWTH 129 



surface down to about 100 fathoms the material obtained 

 from the boring belongs to a continuous series, showing 

 the same mode of arrangement throughout. 



This completes the case for the core, but there still 

 remains another class of objections, which demands our 

 attention. How far is the generally accepted limit of 

 growth of reef-forming organisms to be regarded as 

 exactly known ? The difficulties in the way of deter- 

 mining this limit greatly impressed me during my 

 residence on Funafuti, so that I then wrote : " Not 

 till I had obtained a close acquaintance with the diffi- 

 culties of dredging on the steep sides of an atoll did I 

 recognise on how frail a basis our accepted conclusions 

 rest. It is a task difficult enough to get up corals from 

 the lagoon in comparatively shallow water ; from the 

 sides of the reef it is well-nigh impossible. To obtain 

 dead corals from great depths proves very little ; living 

 corals are generally found with dead associates, and the 

 latter are the more readily detached and brought to the 

 surface."* Neither difficulties nor dangers, however, 

 seem to have had any meaning for Professor David 

 and his colleagues, Messrs. G. H. Halligan and A. E. 

 Finckh. Armed with various ingenious devices they 

 ventured themselves in a frail boat on the outer waters 

 of the reef and brought up from its face all that is 

 essential for us to know. The results are completely 

 in accord with those previously obtained, and have 

 entirely dispelled any misgivings I may have once 

 entertained. 



Thus the following inferences appear to have been 

 established by the investigation of the atoll : 



1. The limit of reef-building growth does not exceed, 

 if indeed it reaches, a depth of 45 fathoms below the level 

 of the sea. 



* Proc. Boy. Soc., vol. Ix. p. 512, 1897. 



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