554 Implantation of Actively Proliferating Epithelium. 



often contains numerous pigment granules (fig. 8), and sometimes presents 

 a vacuolated character (fig. 7). 



It may here be observed that, when epithelial proliferation is produced in 

 the rabbit's ear by the injection of scharlach E (fig. 4), the nuclei of the 

 corium are increased and mononuclear cells rich in cytoplasm become 

 observable. That this is not due to the action of scharlach E, is shown by 

 the fact that repeated attempts to obtain such cell infiltration by injection of 

 this dye, dissolved in olive oil, into the deeper layers of the subcutaneous 

 tissue and also into the testis of the rabbit failed. It follows, therefore, that, 

 as the result of the more active metabolism of the prickle cells under the 

 influence of scharlach E, a cheniiotactic action is set up, leading to the 

 appearance of these cells. 



The implanted normal corium in the second and third series of experiments 

 did not excite any marked chemiotactic response, no invasion of new cells into 

 it being noted. The cartilage survived in most implantations ; when it 

 underwent necrosis, however, it did not become invaded by new cells, its 

 hyaline substance remaining as an inert body, and its nuclei becoming 

 shrivelled and staining indistinctly. 



Summary. 



1. During the first 7 to 14 days after implantation of actively proliferating 

 epithelium of the rabbit's ear, mitosis proceeds apparently undiminished in 

 amount in such portions of the prickle layer as escape necrosis. 



2. In contrast to living prickle cells, dead prickle cells, when implanted 

 under the skin, exert a powerful chemiotactic action, determining at first the 

 appearance of polynuclear cells and later of large mononuclear and giant 

 cells ; before the latter the dead prickle layer slowly disappears. Even 

 living prickle cells, when actively proliferating under the influence of 

 scharlach E prior to implantation, induce chemio tactically, through their 

 increased metabolism, the appearance of numerous cells, mostly mono- 

 nucleated, in the subjacent corium; this is, however, much slighter in 

 degree than that induced by dead proliferated epithelium. 



3. No metaplasia of actively proliferating epithelium occurs as a result of 

 implantation. 



4. Horny epidermic scales and hair shafts remain intact, behaving as inert 

 bodies. 



