186 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 



IV. Origin of Epithelium. — The question whether epi- 

 thelium alone can generate or regenerate epithelium, or 

 whether it may not sometimes be formed from connective 

 tissue elements, lies at the foundation of very important 

 problems of pathology, and even of surgery. We take from 

 the ' Medical Record' (p. 466, 1873) the following summary 

 of the evidence furnished by the modern practice of " skin- 

 grafting : " 



" Considerable difference of opinion still exists regarding 

 the histology of this subject. Page, in the ' British Medical 

 Journal,' December, 1870, thought that he had established, 

 by microscopic investigation, that the epithelium of the skin- 

 graft comported itself in the same manner as ordinary cica- 

 tricial epithelium ; and Jacenko (of KicAv) stated that he 

 found a multiple nucleus in the interior of the cells of the 

 Malpighian layer of the skin-graft. But most observers 

 deny the theory of proliferation. M . Poncet and M. Colrat 

 have both given papers founded on microscopic study, which 

 appear separately in the ' Lyon Medical,' and these observers 

 arrive at conclusions nearly similar to those expressed by M. 

 Reverdin in his essay which appeared in the 'Archives 

 Generales de Medecine ' (March, May, and June, 1872). M. 

 Keverdin, on examining the graft forty-eight hours after it 

 had been transplanted, saw that granulations were separated 

 from the graft, and plunged down between the body of the 

 graft and the embryonic tissue of the ulcer, -with which the 

 granulations ultimately coalesced to form a single tissue. To 

 these prolongations he gave the name of 'bourgeons d'en- 

 chassement,^ or stilt granulations.' He next describes the 

 formation of the cicatrix round the graft. The cells, spring- 

 ing from the graft, have apparently only one nucleus, and he 

 never saw any appearance of it dividing, so that there is 

 nothing to indicate a proliferation of the elements, and in 

 this MM. Poncet and Colrat agree with him. And M. 

 Reverdin further states, seeing that there is nothing to indi- 

 cate formation of cells from a blastema, that the only hypo- 

 thesis at which he can arrive is, that the transplanted 

 epidermis determines, by its presence, the transformation of 

 the embryonic cells of the granulations into epidermic cells ; 

 that is to say, that the epidermis of the graft will only form a 

 mould or model to the embryonic cells. In practising zoo- 

 grafting, however varied the animals were from which he 

 obtained the grafts, they always produced the same kind of 

 cicatrix, namely, the ordinary cicatricial tissue found in man. 



" Opposed to this view, we have the theory which ascribes 

 the principal role in the production of the cicatrix to the con- 



