364 G. HAROLD DREW 



As the actual disintegration of the ripe ova in the course of the 

 degenerative changes occurs very slowly, the invasion of fibro- 

 blasts causes the ova to become completely surrounded by new 

 fibrous tissue. Thus are produced a number of minute cysts 

 containing very few ova, or possibly only one. Subsequently 

 these cysts become lined with columnar ciliated epithelium, de- 

 rived from the innermost layer of fibroblasts forming the cyst 

 wall, in the manner already described. 



It often happens, even when the whole implanted mass becomes 

 encysted, that small aggregations of ova near the outside form sep- 

 arate cysts, and also develop a fining layer of ciliated epithelium. 

 Similarly when small pieces of ovary are implanted, the fibro- 

 blasts, by traveling along any connective tissue framework pres- 

 ent in the ovary, may divide the whole cyst into several parti- 

 tions separated by thin layers of fibrous tissue, which subsequently 

 also form ciliated epithelium. 



EXPERIMENTS TO DETERMINE THE RELATION OF THE PRESENCE 

 OF OVARIAN TISSUE TO THE FORMATION OF CILIATED 

 EPITHELIUM FROM FIBROBLASTS 



An attempt was made to cause the formation of ciliated epi- 

 thelium by the implantation of portions of the ovary that had been 

 killed in various ways, but all these were unsuccessful. The 

 following methods were tried: 



1 . Heat. Small portions of the ovary were boiled in sea water 

 for various times ranging from 2 minutes to 15 seconds, and then 

 implanted in the muscle in the usual way. A considerable inflam- 

 matory reaction resulted, followed by extensive formation of 

 fibrous tissue : a very large proportion of the animals died within 

 a week of the implantations, and often the track of the needle did 

 not heal up. In none of these experiments did the animals sur- 

 vive for more than 15 days, and in all these there was an opening 

 leading to the surface from the implanted tissue. 



Pieces of the ovary that had been heated for two minutes to 

 70°, 60,° 50,° and 45° C. before implantation gave similar results, 

 but heating to 40° C. for two minutes in some cases did not affect 



