132 PEARLS [CH. 



remained in Ceylon to continue the work and was 

 later (1904) appointed Marine Biologist to the 

 Government. 



There is no need to give more than a brief 

 summary of the chief points of Herdman's conclu- 

 sions from his preliminary report (1902) to the 

 'Government of Ceylon. They are as follows: 



"1. The oysters we met with seemed on the whole to be very 

 healthy. 



2. There is no evidence of much disease of any kind. 



3. A considerable number of parasites, both external and internal, 

 both Protozoan and Vermean, were met with, but that is not unusual 

 in molluscs, and we do not regard it as affecting seriously the 

 oyster population. 



4. Many of the larger oysters were reproducing actively. 



5. We found large quantities of minute " spat" in several places. 



6. We also found enormous quantities of young oysters a few 

 months old on many of the Paars. On the Perij^a Paar the number 

 of these probably amounts to over a hundred thousand million. 



7. A very large number of these young oysters never arrive at 

 maturity. There are several causes for this : — 



8. They may have natural enemies, some of which we have 

 determined. 



9. Some are smothered in sand. 



10. Some grounds are much more suitable than others for feeding 

 the young oysters, and so conducing to life and growth. 



11. Probably the majority are killed by overcrowding. 



12. They should therefore be thinned out and transplanted. 



13. This can easily and speedily be done, on a large scale, by 

 dredging from a steamer, at the proper time of year, when the young 

 oysters are at the best age for transplanting. 



14. Finally, there is no reason for any despondency in regard, to 

 the future of the pearl oyster fisheries, if they are treated scientifically. 



