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On Mitosis in Proliferating Epithelium. 

 By J. 0. Wakelin Barratt, M.D., D.Sc. Lond. 



(Communicated by Professor C. S. Sherrington, F.R.S. Received April 4, — 



Read May 30, 1907.) 



(From the Cytological Laboratories, University of Liverpool.) 



The object of the present investigation is to determine the character of the 

 mitosis occurring in cutaneous epithelium which has been artificially stimu- 

 lated to proliferate freely. In the epithelial proliferation of carcinoma, in 

 addition to somatic mitosis, a synaptic mitosis is also met with.* In 

 attempting to decide upon the significance to be attached to this latter 

 phenomenon it is necessary to ascertain whether reduction mitosis is met 

 with exclusively in cancerous proliferation of the surface epithelium, or 

 whether it is also encountered in non-cancerous proliferation. If it is present 

 in the latter case, then synaptic mitosis cannot be regarded as exclusively 

 related to epithelioma, or, for that matter, to sexual reproductive tissue ; if, 

 however, only somatic mitoses occur in non-cancerous epithelial proliferation, 

 then the possibility is present that the altered biological characters 

 presented by the epithelial cells of malignant growths may be in some way 

 directly connected with the reduction taking place in the number of 

 chromosomes. 



The abundant epithelial proliferation occurring in many cutaneous diseases, 

 e.g., psoriasis, lichen planus, and dry forms of eczema, is unsuitable for this 

 investigation, since the amount of material available from such sources is too 

 small and the supply too inconstant to fulfil the requirements of research. 

 Recourse was therefore had to epithelium, which had been made to proliferate 

 freely by the use of scharlach R,f dissolved in olive oil, the injection of which 

 beneath the skin of the rabbit's ear causes extreme and, it may, irregular 

 hypertrophy of the Malpighian layer.j It was further found of advantage in 

 obtaining an abundance of division figures to implant pieces of such 

 proliferating epithelium under the skin of the rabbit. Using the material 

 obtained in these two ways the present investigation was carried out. The 

 effect of scharlach R, it may be observed, is to cause marked increase of the 

 prickle layer, both of the surface epithelium and of the hair follicles. This 

 increase is at first fairly regular, but later, when considerable in degree, 



* Farmer, Moore, and Walker, ' Roy. Soc. Proc.,' B, vol. 77, p. 226. 

 t Scharlach R is azo-orthotoluol-azo-/3-naphthol : C 7 H 7 N = NC-H 6 N 

 % B. Fischer, ' Munch. Med. Wochenschr.,' 1906, 53. Jahrg., S. 2041. 



