EXPERIMENTAL METAPLASIA 361 



eration. The cells of the germinal epithelium, the connective 

 tissue cells, and the cells lining the oviduct, lose their normal 

 appearance, the chromatin of the nuclei becomes aggregated into 

 small darkly staining masses, and the outline of the cells becomes 

 less distinct, the cilia of the oviducal epithelium soon vanish. 

 Coincidently the whole mass of tissue is invaded by blood corpus- 

 cles which exercise a phagocytic action and slowly remove the 

 degenerated material. The mature, or nearly mature, ova show 

 a much greater resistance to this degenerative process than any 

 of the other cells. 



Thus, after the lapse of about three days from the implanta- 

 tion, we have a mass of ovarian tissue which is invaded by phago- 

 cytes and shows signs of degeneration, and is surrounded by a 

 layer of fibroblasts forming a definite cj^st wall. The fibroblasts 

 are mostly oval in shape, with little or no perceptible amount of 

 cytoplasm, and have not taken on the appearance they present 

 in the resting state. 



From the fourth to the sixth day degeneration of the ovary con- 

 tinues, and when cyst formation takes place, as in the cases here 

 described, the degeneration is complete and every trace of organ- 

 ised structure has vanished by the sixth day. When the degen- 

 erative changes are complete, the site of the implanted ovarian 

 tissue is occupied only by blood cells, and by a granular substance, 

 which must either be formed during the process of degeneration, 

 or be left after all the other substances composing the ovarian 

 tissue have been rendered soluble and so have escaped from the 

 cyst. If the cyst is cut open, and the contents examined under 

 the microscope, it is seen that the granular matter is of an orange 

 color, and that many of the blood corpuscles have iiigested par- 

 ticles of this substance. As the orange color of the cysts remains 

 unchanged, and undiminished in intensity, even after fourmonths, 

 it appears that this substance is unable to escape from the cyst 

 through the surrounding layer of fibrous tissue, and the same must 

 hold true for blood corpuscles within the cyst, which have ab- 

 sorbed this substance by phagocytosis. It seems probable tha^ 

 such blood corpuscles, after ingesting grahules of this^substance, 



