234 POPULAR SCIENCE MONTHLY. 



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 Periya Paar the number 

 of these probably amounted 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 have many 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 be easily and speedily 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 scientific- 

 ally. The adult oysters are plentiful on some of the paars and seem 

 for the most part healthy and vigorous; while young oysters in their 

 first year, and masses of minute spat just deposited, are very abun- 

 dant in many places. 



To the biologist two dangers are however evident, and, paradoxical 

 as it may seem, these are overcroioding and overfishing. But the 

 superabundance, and the risk of depletion are at the opposite ends of 

 the life cycle, and, therefore, both are possible at once on the same 

 ground — and either is sufficient to cause locally and temporarily a 

 failure of the pearl oyster fishery. What is required to obviate 

 these two dangers ahead, and ensure more constancy in the fisheries, 

 is careful supervision of the banks by some one who has had sufficient 

 biological training to understand the life-problems of the animal, 

 and who will therefore know when to carry out simple measures of 

 farming, such as thinning and transplanting, and when to advise as 

 to tbe regulation of the fisheries. 



In connection with cultivation and transplantation, there are 

 various points in structure, reproduction, life-history, growth and 

 habits of the oyster which we had to deal with, and some of which 

 we were able to determine on the banks, while others have been the 



