65 



showed that the colouring matter was taken up by the 

 amoeboid blood cells, and that these wandering cells 

 containing the pigment were to be found in the heart, in 

 some of the blood-vessels and in aggregations in " cysts " 

 under the surface epithelium of the body. He describes 

 the colour (in the ventricle) as a " delicate pea-green," 

 and states that it is not chlorophyll nor diatomine : he 

 suggests that it may be phycocyanine or some allied 

 substance. 



In 1886, Bay Lankester* gave a useful summary of some 

 of the earlier papers, and discussed the main questions 

 concerned. Moreover he investigated the gills of the 

 green oyster histologically, and described cells laden with 

 green granules which occur in the epithelium of the gills 

 and labial palps. He showed that such cells are also 

 present in the common oyster, where, however, they are 

 not green, and that these cells may be found also wandering 

 over the surface of the gills. He considered them as 

 " secretion " cells, but they are clearly the same structures 

 which Ej'der a few years before had found in the blood, 

 Lankester found the Navicula in the intestine of the 

 green oyster, and re-asserted that there was no copper 

 and no iron in the refractory blue pigment — which he 

 described under the name " marennin." 



Quite recently, Chatin, de Bruyne, and others have 

 re-investigated the structure of the oyster's gill and the 

 process of greening in more detail, with the general result 

 that the large cells (macroblasts) containing the green 

 granules are now regarded as "phagocytes" conveying 

 some substance to the surface of the body. One author, 

 however, Carazzi, considers that the macroblasts are 

 surface cells, which are taking up substances from without 

 for purposes of nutrition, and he attributes the green 



* Quart. Jouni. Miur. Sci., Vol. XXVI., p. 71. 



