OYSTER CULTURE IN AMERICA. 823 



vived and increased while contending with them. There- 

 fore, an increase of power for injury must be assigned to 

 one or all of these, to account for the diminished number 

 of oysters. Probably the " spat" falls on more favourable 

 ground since the beds were discovered than w r as formerly 

 the case, owing to the increased amount of " cultch" due 

 to the fishing of the beds, and aside from that, the con- 

 ditions surrounding and operating upon the beds are so 

 similar to those in the past that the loss of the young 

 could not be much greater from the want of attachment. 



Discarding the theories of " the freshets and other 

 natural causes, the ravages of enemies, including astjris 

 (and especially the latter as the principal causes), for the 

 deterioration of the beds," Lieutenant Winslow proceeds : 

 But as there is also a marked deterioration upon those beds 

 upon which no drills were found, still another cause must 

 be at work, and must be sought in the non-production of 

 the young. 



This is caused by the failure of the " brood" oysters, 

 they having removed or become extinct, thus causing a 

 failure of impregnation. If the theory is correct that there 

 is a mutual fecundation, partaken of by all oysters on the 

 beds, the spermatozoa being formed and milted somewhat 

 prior to the formation of ova, then it can easily be under- 

 stood that if the oysters are so much separated that even 

 the tides and currents cannot bring the spermatozoa within 

 reach of the adjacent animals, there could be no produc- 

 tion of young. 



Taking for instance the most exaggerated case in both 

 Sounds, that of the Muddy Marsh Bed, it will be seen that 

 the set of the current over it not generally from any 

 adjacent bed, the nearest one being Parker's Rock, which 

 is over three miles distant ; the oysters on the Muddy 



