118 THE ZOOLOGIST. 



EDITOEIAL GLEANINGS. 



At the meeting of the Zoological Society, on the 4th inst., Dr. H. 

 Lyster Jameson, M.A., read a paper " On the Origin of Pearls." The 

 author's observations referred especially to Mytilus eclulis, the Common 

 Mussel. The pearls were found to be due to the presence of parasitic 

 Distomid larvae, which entered the subcutaneous tissues of the Mussel, 

 and became surrounded with an epidermal sack similar in its characters 

 to the outer shell-secreting epithelium of the mantle. If the Distoma 

 died in the sack it became calcified, and formed the nucleus of a pearl, 

 the pearl arising, like the shell itself, from the calcification of the 

 cuticle of the epithelial cells. The parasite sometimes migrated out 

 of the sack, in which case the nucleus of the pearl was inconspicuous. 

 Dr. Jameson had investigated the life-history of this parasite, and 

 found that it arose as a tail-less Cercarian larva, in sporocysts, in Tapes 

 decussatus and Cardium edh.de. He had succeeded in infecting Mussels 

 from Tapes in an aquarium. The adult stage of this parasite was 

 apparently Distoma somatiim, Levinsen, which occurs in the intestine 

 of the Eider-Duck, and which the author had found in the Scoter or 

 Black Duck (CEdemia nigra). The complicated life-history of the 

 parasite, and the absence of organs of locomotion in the Cercaria- 

 stage, sufficed to account for the anomalous and hitherto inexplicable 

 distribution of pearl-bearing Mussels. Dr. Jameson had found that 

 pearls were caused by similar parasites in several other species of 

 Mollusca, including some of the Pearl-Oysters ; and he believed that 

 the artificial infection of the Pearl- Oysters could be effected in a 

 similar manner to that which he had found successful in the case of 

 the Common Mussel. When this was achieved the problem of arti- 

 ficially producing pearls would be solved. 



Slowly but steadily the great collection of British Birds by Mr. F. 

 Coburn, the well-known taxidermist, of Birmingham, is being built 

 up. More than ten years have elapsed since the work was first 

 entrusted to him by Mr. Baylis, of Birmingham, and it may be fifteen 

 or even twenty years before the great task is completed. The state- 

 ment suggests dilettante efforts, but, as a matter of fact, hard constant 



