188 The Umty of the Organism 



part of the organism into other tissues of the newly added 

 parts, or through the derivation of tissues of the renewed 

 parts from tissues of another sort in tlie old parts by the 

 latter's first returning to something like an embryonic con- 

 dition ; (3) cases of transformation of tissues in certain 

 pathological growths. 



Under the first head one of the oldest and most frequently 

 cited examples is that of the transformation of the soft 

 mucosa cells lining the vagina into pavement-like cells, when 

 inversion of that organ occurs. A particularly clear and 

 interesting example of cell transformation which may be 

 properly ranged in the same class has recently been reported 

 b}' Harms. This investigator transplanted pieces of the 

 thumb pad of the sexually active male frog {Rana fusca) 

 from one individual to another individual. After about two 

 months he found that complete union of the grafted piece 

 had been effected, and that the epithelial cells of the graft 

 were in a normal condition. The glands, however, peculiar 

 to the epidermis of these pads showed signs of retrogres- 

 sive change. In the course of another month or so the 

 glands had undergone complete transformation into a solid, 

 wellnigh structureless mass, and the cells of the epithelium 

 immediately surrounding them had reformed and rearranged 

 themselves into well-defined encapsulating layers, constitut- 

 ing what Harms designates as a "metaplastically stratified 

 epitlielium." This case appears to be, as the author re- 

 marks, one which "shows all phases of tissue transformation 

 in a way not open to objection." Tliis case is considerably 

 different from those previously cited in that the influences 

 operative in bringing about the tissue changes are more in- 

 timately connected with the cliemico-vital processes of the 

 organism, and are less purely mechanical than in the other 

 cases. Harms does not neglect this aspect of the matter, 

 but a consideration of it would be out of place here. 



Under the second head, one of the most striking and at 



