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 scientifically. 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 abundant in many places.
To the biologist two dangers are however evident, and, paradoxical as it may seem, these are overcrowding 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 the 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
