230 POPULAR SCIENCE MONTHLY. 



banks that might be considered necessary. I arrived at Colombo in 

 January, 1902, and as soon as a steamer could be obtained proceeded 

 to the pearl banks. In April it was necessary to return to my uni- 

 versity duties in Liverpool, but I was fortunate in having taken out 

 with me as my assistant, Mr. James Hornell, who was to remain in 

 Ceylon for at least a year longer, in order to carry out the observations 

 and experiments we had arranged, and complete our work. This pro- 

 gram has been carried out, and Mr. Hornell has kept me supplied 

 with weekly reports and with specimens requiring detailed examination. 



The steamship Lady HavelocJc was placed by the Ceylon govern- 

 ment at my disposal for the work of examining into the biological con- 

 ditions surrounding the pearl oyster banks; and this enabled me on 

 two successive cruises of three or four weeks each to examine all the 

 principal banks, and run lines of dredging and trawling and other 

 observations across, around and between them, in order to ascertain the 

 conditions that determine an oyster bed. Towards the end of my stay 

 I took part in the annual inspection of the pearl banks, by means of 

 divers, along with the retiring Inspector, Captain J. Donnan, C.M.G., 

 and his successor. Captain Legge. During that period we lived and 

 worked on the native barque Bangasameeporawee, and had daily oppor- 

 tunity of studying the methods of the native divers and the results they 

 obtained. 



It is evident that there are two distinct questions that may be 

 raised — the first as to the abundance of the adult 'oysters,' and the 

 second as to the number of pearls in the oysters, and it was the first of 

 these rather than the frequency of the pearls that seemed to call for 

 investigation, since the complaint has not been as to the number of 

 pearls per adult oyster, but as to the complete disappearance of the 

 shell-fish. I was indebted to Captain Donnan for much kind help 

 during the inspection, when he took pains to let me see as thoroughly 

 and satisfactorily as possible the various banks, the different kinds and 

 ages of oysters, and the conditions under which these and their enemies 

 exist. I wish also to record my entire satisfaction with the work done 

 by Mr. Hornell, both while I was with him and also since. It would 

 have been quite impossible for me to have got through the work I did 

 in the very limited time had it not been for Mr. Hornell 's skilled 

 assistance. 



Most of the pearl oyster banks or 'paars' (meaning rock or any 

 form of hard bottom, in distinction to 'Manul,' which indicates loose 

 or soft sand) are in depths of from five to ten fathoms and occupy 

 the wide shallow area of nearly fifty miles in length, and extending 

 opposite Aripu to twenty miles in breadth, which lies to the south of 

 Adam's Bridge. On the western edge of this area there is a steep 



