represented an inflammatory response to a stressful condition and 

 therefore a pathology due to such stress, or if it was a normal condi- 

 tion in the reproductive cycle of C. gigas. This condition was present 

 in only one Cvassostvea virginica from South Louisiana oil platforms 

 (Armstrong et al., 1980) but was observed in other bivalve species (10% 

 of specimens examined in association with degeneration or necrosis of 

 the gonad). Eight female C. gigas from the Pacific Northwest (Sequim, 

 Washington) were examined for comparison. All eight appeared to be in 

 a post-spawn condition and all had heavy aggregation of leucocytes in 

 the gonadal tissues. 



The spawning cycle of the C. gigas from France could not be defin- 

 itely determined. Undifferentiated (could not determine if it was male 

 or female), undeveloped, developing (immature), ripe (mature) and spawned 

 stages were present in samples from all five of the collecting periods 

 (December 1978, April 1979, August 1979, February 1980, and June 1980). 

 The majority of the specimens from December 1978, however, appeared to 

 be of the spawned stage at Aber Wrac'h, ripe at Aber Benoit, and undiffer- 

 entiated at Rade de Brest. In April 1979, the majority of the specimens 

 appeared to be in the developing stage at all three sites. The majority 

 of the specimens taken during August 1979 and June 1980 appeared to be 

 of the ripe stage at all three sites, although there were some spawned- 

 appearing specimens from Aber Wrac'h in August 1979. The February, 1980 

 collection yielded more undifferentiated and developing specimens. This 

 does somewhat indicate an early winter spawn, but as already stated, all 

 reproductive stages were present in samples from all five collection 

 periods. 



In the C. gigas from France, 13.8% (18 of 130) of the gonads 

 examined contained large numbers of leucocytes dispersed throughout 

 the tissues. All 18 incidences were in female gonads (18 of 76 or 23.8%). 

 This condition was present in undeveloped, developing (immature), ripe 

 and post spawn ovaries. In some cases it could not be determined if the 

 ovary was in a developing stage or a post-spawn stage because of the 

 large numbers of leucocytes present. In some, the gonad appeared fully 

 spawned (entire gonad examined contained only a few ova and ovacytes, 

 follicles largely empty), while in others part of the ovary was packed 

 with ova (ripe) and the other part contained few ova and ovacytes 

 (spawned) and many leucocytes. In gonads with large numbers of leuco- 

 cytes, all or almost all ova appeared normal (not degenerating or lysing) , 

 The 29 normal ovaries (no aggregations of leucocytes present) included 

 the undeveloped, developing (immature), ripe and spawned stages. 



Twenty-two of the 130 (16.6%) gonads examined contained compact 

 clumps of leucocytes ranging from foci in the follicular wall to large 



281 



