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ABSTRACTS OF MEMOIRS 



RECORDING WORK DONE AT THE PLYMOUTH LABORATORY. 



Experimental Metaplasia. I. The formation of columnar ciliated 

 epithelium from fibroblasts in Pecten. By G. Harold Drew. 



{Journal of Experimental Zoology, Vol. X, 1911, pp. 349-379.) 



The implantation of small pieces of the ripe ovary of Pecten maximus 

 or Pecten opercularis into the adductor muscle of another animal of the 

 same species was found to result at first in the formation of a closed 

 cyst within the muscle, lined with layers of fibroblasts. Complete 

 degeneration and disintegration of the ovarian tissue within the cyst 

 occurred in a few days, and then the cyst contained only an orange- 

 coloured granular substance, presumably derived from the yolk, and 

 numbers of blood corpuscles. After the lapse of from twenty-one to 

 thirty-two days, changes occurred in the innermost layer of fibroblasts 

 lining the cyst. They reverted to an embryonic type, and afterwards 

 became converted into columnar ciliated epithelium, which formed a 

 continuous layer lining the cyst. The changes resulting in this forma- 

 tion of ciliated epithelium from fibroblasts were followed clearly step 

 by step, and once formed, the ciliated cells persisted unaltered for at 

 least 120 days, which was the longest period for which the animals 

 could be kept alive under experimental conditions. 



Experiments were performed showing that this change is not pro- 

 duced by the implantation of any of the other tissues of Pecten, by 

 neutral foreign bodies which would merely act as a source of mechanical 

 irritation, by the transplantation of the ripe ovarian tissue of other 

 Lamellibranchs, or by the transplantation of pieces of the ovary of 

 Pecten opercularis into the adductor muscle of Pecten maximus, and 

 vice versa. 



Other experiments showed that the development of ciliated epi- 

 thelium does not occur if pieces of the immature or spent ovary be 

 implanted, and that it is prevented by treating the ripe ovary with a 

 suspension of the sperm in sterile sea-water before implantation. 

 Also that it does not occur if the ovary be killed by physical or 

 chemical agents before implantation. A series of experiments were 



