OCCURRENCE IN VIRGINIA OF GREEN-GILLED OYSTERS. 1 45 



o 9. Artificial sea water, 1,000 cc. of HjO, 25 gr. of NaCl, i gr. of MgS04, 5 gr. of CaClo, 1 gr. of NaBr. 

 "10. Artificial sea water, i.ooocc. of H2O, i gr. of HNajPOj, 15 gr. of NaCl, i gr.of NaBr, i gr. of CaClj. 



11. Artificial sea water, same as No. g, with straw and moss added. 



12. Artificial sea water, same as No. 10, with straw and moss added. 



One set of these solutions was kept at room temperature and another at approxi- 

 mately 26° C. 



The solutions which contained the dextrose, lactose, and oyster broths were ster- 

 ilized to prevent too flourishing bacterial growth. The broths here mentioned were 

 those used in bacteriological work. 



These solutions were then inoculated with a considerable quantity of diatoms of 

 different species, but in no case did any reproduce, though some lived at least three 

 days in the new envirormient. 



From observations of the water samples from Virginia it was noted that continual 

 slight motion of the water sample and aeration tended toward prolonged life of the 

 diatoms. 



Further experiments on the isolation and artificial cultivation of these and other 

 diatoms are projected. 



THE CHEMISTRY OF GREEN-GILLED OYSTERS. 



The only chemical work that had been done on the green pigment of Marennes 

 oysters at the time of this investigation was summed up in Lankester's work. That 

 work shows that the pigment was insoluble in water, dilute acids, dilute alkalies, alcohol, 

 ether, glycerine, and benzol, either hot or cold, and that the coloration was not due to 

 the presence of copper or any other metallic element. It shows further that strong 

 acids or alkalies dissolved but at the same time destroyed the pigment. 



Lankester examined spectroscopically green-gilled tissue with the use of a powerful 

 ray of light. He found, however, that this demonstrated no isolated absorption bands 

 in the spectrum. He also examined in like manner a mass of Navicula ostrearia, but 

 detected no absorption bands in the spectrum. 



The first investigations in this problem carried on in respect to the chemistry of the 

 greengills was to ascertain whether or not there was any copper present in the gills. 

 Four grams of desiccated greengill were digested in sulphuric acid and potassium nitrate. 

 After complete digestion, and after making the solution ammoniacal, only the faintest 

 trace of yellowish-green color could be detected. This test showed the absence of all 

 but the faintest trace of copper, which has been found to be present in all oysters. This 

 experiment was repeated with the same result. Lankester said in this connection: 

 "Whilst there are so many considerations which explain the origin of the notion that 

 copper may be responsible for the green color of the 'huitres de Marennes,' although that 

 metal has nothing to do with it, it is extremely remarkable as a coincidence that of late 

 years it should have been established that copper in minute quantities is a normal con- 

 stituent of the blood of molluscs." Further evidence that the greengill contained no 

 abnormal amount of copper was seen in the fact that the people of the vicinity who ate 

 the oysters raw in considerable quantities noticed no abnormal taste. Surely had the 

 green color been due to a copper compound, there would have been enough present in 

 specimens so intensely pigmented to have given the so-called coppery taste that many 

 observers claim is characteristic of oysters containing excessive copper. 



09 and 10 contained also a considerable quantity of dead diatom material. 



