318 



DR. H. LYSTEU JAMESON ON 



forming a hemispherical, or sometimes rather more than 

 hemispherical pearl-like excrescence, attached to the shell by its 

 base. These " Culture Pearls " are produced in large numbers, 

 and find a ready market for purposes for which " half-pearls " are 

 used. They are now familiar objects in Europe *. 



Text-figure 39 is a section of a Japanese " Culture Pearl," 

 which I purchased in London, while still attached to the shell, 

 and decalcified. 



Text-fia-. 39. 



TLOjC. 



nac. 



col.' ruic. pr. 



Section tlirongli a decalcified Japanese " Culture Pearl " still attaclird to the shell. 

 nil., the artificial "nucleus," a bead of nacre, the ]amina3 of the nacre being 

 cut transversely ; j9r., prismatic layer ; nac, original nacreous lining, which 

 existed before the nucleus was introduced; mac. ', more recent nacre, lining the 

 shell and extending over the " nucleus " to form the '' Culture Pearl," 

 secreted after the introduction of the nucleus ; nac." , nacreous layers where 

 the lining of the shell is carried over the nucleus; col., col.', repair-substance 

 secreted in a zone around the point of contact between nucleus and shell, 

 where the deposition of the shell-substance was not controlled by the 

 mantle ; gr., granular matter, perhaps of foreign origin or of the nature of 

 amorphous substance. X 10. 



The " nucleus" has been very skilfully introduced, so that there 

 is practically no trace of " dirt " between it and the nacreous 

 layer with which it is invested, as is so often the case in the 

 ■" blisters " which have been produced by naturalists and experi- 

 menters from time to time. Moreover, the disturbance of the 

 normal functions of the mantle has been so slisfht that, in the 



* Needless to saj^, these bodies are not " Pearls," biologically speaking, but 

 belong to the class of structures to which I have applied the name " blisters," 

 familiar on the Australian Fisheries and in the Trade. Various naturalists have 

 ■pi-oduced such bodies from time to time. I have recently seen some very beautiful 

 •ones produced in Margaritifera maxima, and I myself produced some prt>sentable 

 ones in Margaritifera margaritifera in Papua in 1899-1900. But although 

 .attempts have been made, and are still being made, to do this on a commercial scale, 

 I am not aware that commercial success has j'et been achieved aiij'where else than 

 , in Japan; indeed, I think that the combination of circumstances which has led to 

 ■thesu.ccess oftheJapawese enterprise — viz., skill, patience, and intelligence, backed by 

 the best scientific advice and suiiported by cheap labour — has generally been lacking 

 in other ventures. I may add that the price that could be obtained for the best of 

 these gems is insignificant compared with the value of a real pearl of like size. No 



