EXPERIMENTAL METAPLASIA 367 



species into Pecten maximus or Pecten opercularis in every case 

 caused death in a very short time. Such experiments were tried 

 with the ovary of Cardium edule, Cardium norvegicum, Glycim- 

 eris glycimeris, and various species of Tapes and Venus. On the 

 other hand, after the transplantation of the ovary of Pecten oper- 

 cularis into the muscle of Pecten maximus and vice versa, the ani- 

 mals survived indefinitely, but there was no development of cil- 

 iated epithelium within the cysts formed round the ovarian tissue. 



The implantation of portions of the male gonad produced a 

 violent inflammatory reaction, with subsequent very extensive 

 formation of fibrous tissue for some distance around the site of 

 implantation. No cyst formation took place, and no trace of 

 the spermatozoa could be seen in sections made three days after 

 the experiment. The implantation of large pieces of the testis 

 (more than about 1 mm. in diameter) usually caused the death 

 of the animal in three or four days. 



If small pieces of the ripe ovary be placed in sterile sea water 

 containing a little sperm, then well washed and implanted, a sim- 

 ilar inflammatory reaction and free formation of fibrous tissue 

 results, only a small proportion of the animals survive, and in these 

 no formation of ciliated epithelium occurred. Similarly, if some 

 days after implantation of pieces of the ovary, a little sperm 

 suspended in sterile sea water be injected with a hypodermic 

 syringe into the exact site of the original implantation, inflam- 

 mation and free fibrous tissue formation is set up, and the ovarian 

 tissue is either absorbed, or becomes surrounded by a large area 

 of dense fibrous tissue, and again the formation of ciliated epi- 

 thelium is prevented. 



With the object of eliminating the possibility of the formation 

 of the ciliated epithelium lining the cysts from the epithelium 

 covering the adductor muscle, which conceivably might have 

 been invaginated by the introduction of the transplanting needle, 

 a series of experiments was undertaken in which the implanta- 

 tion was made through a hole bored in the shell, and afterwards 

 closed with sealing wax in the manner previously described. In 

 these experiments the ciliated epithelial lining of the cysts devel- 

 oped in exactly the same way as when the implantation was made 

 laterally through the muscle.. 



