ABSTRACTS OF MEMOIRS. 573 



made to eliminate the possibility of the origin of the ciliated epi- 

 thelium lining the cysts from the ciliated cells of the oviduct, which 

 might be present in pieces of the ovary that were implanted, or from 

 the layer of epithelial cells forming the outer coating of the adductor 

 muscle, which might be carried inwards by the transplanting needle. 



It thus appears that the conversion of fibroblasts into ciliated 

 epithelium is a specific reaction following the implantation of the ripe 

 living ovary. 



These observations were the result of nearly a thousand experi- 

 ments, of which the majority were performed on Peden (ypercularis. 



It appears that this conversion into ciliated epithelium of the inner 

 layer of fibroblasts lining a cyst formed round a piece of the ovary, 

 which has been implanted into the adductor muscle of Pecten, is a 

 specific reaction that occurs only when the ripe living ovary of an 

 animal of the same species is implanted. The reaction takes place 

 long after all trace of organized structure in the implanted tissue has 

 disappeared, and it is difhcult to conceive of its being due to any other 

 cause than the presence of some definite chemical substance within 

 the cyst, which is characteristic of, and specific for, each species. 



Examination of the contents of the cysts showed, in all cases where 

 the development of ciliated epithelium had occurred, tliat an orange 

 granular substance, and blood corpuscles in various stages of degenera- 

 tion, were present. These orange granules resembled in appearance 

 the orange-coloured yolk substance of the ripe ova, and the amount of 

 this granular substance within the cysts seemed to be independent 

 of the length of time during which the implanted tissue was allowed 

 to remain in the muscle. If implantation of pieces of the ovary of 

 approximately equal size were made, examination of the contents of 

 a cyst after six days showed as much of this substance present as in a 

 similar cyst after 120 days ; hence it appears that this substance can- 

 not escape through the cyst wall. When it is considered that the 

 development of the ciliated epithelial lining only occurs as a reaction 

 to the implantation of ripe ova, containing a plentiful supply of the 

 orange-coloured yolk substance, there is at least a possibility that the 

 orange substance within the cysts bears a close chemical relation to 

 the yolk substance, and that the development of ciliated epithelium 

 from the fibroblasts lining the cyst is a specific reaction to its presence. 



Though admittedly based on no experimental evidence, it is sug- 

 gested as a possible explanation of the phenomena that some sub- 

 stance is formed as a result of the ingestion of these orange granules 

 by the blood corpuscles, and their subsequent degeneration within the 

 cyst : that the granules themselves remain unchanged, and are again 



