25 



seems very probable that the poisonous effects of mara pant completed the 

 destruction of the Kuranji and Kadero beds in 1890. These beds have never 

 recovered, a result due in the first instance to the destruction having been so 

 complete in this neighbourhood that no spat was available for years and next 

 to the fouling of the old cultch owing to the uninterrupted growth of a rich 

 marine fauna. To-day the ground is foul and unsuitable in its present 

 condition to the settlement of new spat. 



105. The condition of the beds generally is bad, but far from hopeless. 

 The Sind oyster has many good qualities ; it is of excellent flavour, attains a 

 marketable size very quickly and fattens rapidly. Two years are sufficient to 

 rear it from spat to a size and quality suitable for table use. It is a species 

 which undoubtedly will respond satisfactorily to culture ; the cultural system 

 may be of the simplest, indeed the conditions preclude any elaboration. Some 

 experiments in epat collection have already been made ; they have been 

 considered failures, but enough is known of their results some are patent to the 

 eye to-day in the Vad creek and at Nawa Nar 'to enable us to say that 

 they might easily have been turned into successes had a little expert knowledge 

 been available and had the condition of the experiments been recorded 

 systematically. As it is, tiles bearing oysters of good size may now be picked up 

 on the site of these experiments and the complaint has been made on several 

 occasions that the experiments have been rendered of no account by systematic 

 theft of the oysters which have grown upon the tiles. Myself, I read the story 

 otherwise ; the fact that the tile oysters were stolen repeatedly is evidence that 

 these tile-raised individuals, the product of artiflcal methods, were sufficiently 

 well grown to be worth collecting for market. Instead of discouragement, thia 

 fact should have spurred to further effort and to experiments on a larger and 

 more systematic plan. The mistake seems to have been that it was not clearly 

 recognized that the aim of first experiments should be directed solely to 

 ascertain data ; before practical culture can be started successfully we must 

 have clear knowledge of the season at which the oysters spawn and of the 

 physical factors which control or stimulate the simultaneous emission of milt and 

 ova by large numbers of individuals massed in a bed. When we have ascer- 

 tained the principal elementary facts relating to spawning then only are we 

 justified in undertaking practical work; otherwise anything we do is a blind 

 groping in the dark, a proceeding apt to lead to failure and the discredit of 

 what is really an economically sound proposition. 



106. The enquiry now ended has however furnished a certain amount of 

 useful information concerning these beds and this, together with a fairly intimate 

 acquaintance with the methods found successful in districts where oyster 

 culture is systematically pursued, enable me to suggest the lines on which 

 experiments are most likely to be successful, to forecast thwir results and to 

 state a number of cardinal principles to be observed in the regulation as well as 

 in the culture of the beds. 



107. From dissection of a number of the oysters I found the sexes to bo 

 separate as in the common mud oyster of Southern India and in the Portuguese 

 oyster (O. angulata) of Western Europe. As in these two species the ova and 

 sperm are discharged when ripe into the surrounding water where fertilization 

 takes place and where embryonic development proceeds ; in the English oyster, 

 O. edulis, fertilization of the ova takes place within the gills of the parent and 

 the young remain there till they develop all the larval organs. When the 

 larvae of O. edulis swim away from the parent they are capable of immediate 

 attachment to any suitable cultch they may encounter ; in the case of our 

 Indian edible oysters owing to the absence of any incubatory phase, the free- 

 swimming period of life is prolonged and several days must elapse before 

 development is sufficiently advanced to permit of attachment to cultch. Five or 

 six days elapse before settlement is possible and when suitable surfaces are 

 scarce the free swimming stage may be extended to double this period. We 

 urgently require precise information regarding the season when general or 

 wide-spread spawning occurs. In Europe and in the United States, that is, in 

 temperate latitudes, it occurs when the shallow coastal waters warua with the 



B 695-7 



