10 CEYLON PEARL OYSTEK REPORT 



where, with the assistance of Mr. Walter Tattersall, B.Sc., and Mr. J. Pearson, B.Sc. 

 (in Octoher, L902), an independent examination of them was made, with results thai 

 do not altosrether agree with JJr. Jameson's. 



We may distinguish between four kinds of mussels examined by both of us, and 

 described by Jameson as follows : 



(A) From the beds opposite the Piel Hatchery " where every specimen is 

 abundantly infected .... and almost every specimen contains pearls." 



(B) From the piles of the old pier at Piel " practically without parasites." 



(C) From Roosebeck Scar, outside Barrow Channel " not infected." 



(D) Roosebeck Scar mussels transplanted to foreshore at Piel two years ago " all 

 were infested " .... " each contained several small pearls." 



Of (A) we examined a sample of 25 mussels which contained in all 151 pearls and 



1 1 parasites, but 4 of the specimens had neither pearls nor parasites and no less than 

 18 out of 25 had no parasites. We cannot therefore agree that " every specimen 

 is abundantly infected." 



Of (B) we examined also 25 mussels, which showed in all 21 pearls and 22 parasites, 

 7 had neither pearls nor parasites, and 13 had no parasites. These, then, showed far 

 fewer pearls than (A), but twice as many parasites, and fewer of them were free from 

 infection. They can scarcely be called " practically without parasites." 



Of (C) we examined 28 mussels, which contained 73 pearls and 37 parasites, 4 had 

 neither pearls nor parasites and only 9 (out of 28) had no parasites. These, then, are 

 evidently just as much infected as the mussels on the Piel foreshore (A). 



Of (D) we examined 24 mussels, and they contained 65 pearls and 26 parasites, 

 3 had neither pearls nor parasites and 12 out of 24 had no parasites. So in place of 

 these transplanted " Roosebecks " having become more infected on the Piel shore, 

 they on the whole showed rather less infection than the mussels taken direct from 

 the parent bed. 



Finally, we examined a sample of 25 cockles from Piel, and found in them 8 pearls, 

 but no parasites at all of the right kind. This does not support the view that the 

 cockle contains the earlier stage of the parasite and passes it on to the mussel. 



At the end of October, 1902, Mr. Andrew Scott, A.L.S., and Mr. James 

 Johnstone, B.Sc, examined some further samples at Piel with the following 

 results : 



(A) Examined 61, got 390 pearls and 191 parasites. 



(B) 103, 100 61 

 (D) 53, ,,161 66 

 (Roosebeck Scar mussels could not be got at the time.) 



fr Mr. JOHNSTONE, however, informed me that before he made this examination a gale had washed away 

 some of the piles of the old pier, and that, consequently, his sample of (B) was obtained from rather a 

 lower level than JAMESON'S and so may have contained more parasites. 



