396 Tumors. 



initial stages of skin cancers, by the intrusion of connective tissue, 

 stimulated to proliferation by inflammation, between the epithelial 

 cells. In other words, according to Ribbert cancers always start on 

 a base of chronically inflamed tissue. The epithelial cells do not 

 make the initial penetration into unaltered connective tissue ; the 

 primary change being the inception of the inflammatory prolifera- 

 tion of the subepithelial connective tissue, which raises the epithe- 

 lium and, as the proliferating connective tissue elements invade the 

 deeper epithelial layers and destroy the intercellular cement, 

 separates isolated cells from their proper relations and thus mis- 

 places them. The isolated epithelium, now situated in the midst 

 of the connective tissue and sufficiently nourished by it, begins 

 to nuiltiply ; and, being prevented from growing upward toward 

 the surface of the skin or mucous membrane, and its relations with 

 the general epithelial tissue, its nerves and normal substratum 

 (papillary layer) being destroyed, it must necessarily penetrate 

 irregularly into the tissues along the course of the lymph spaces. 

 Thus it comes to force its radicles and cords in every direction 

 and to form the beginning of the cancer. 



As a matter of fact cancers do occur with frequence in places 

 where for some time previously inflammatory irritation has existed. 

 In man, for example, cancer of the lip is especially likely to be met 

 in persons who smoke pipes habitually, and, too, just in the corner 

 of the mouth which is always exposed to irritation from the juices 

 from the pipe. The influence of soot as an irritant capable of in- 

 ducing cancer is well seen in chimneysweeps (chimney sweep's can- 

 cer) ; and that of paraffine has become well known among the em- 

 ployees of parafline factories as causing epidermoidal proliferations 

 (paraffine cancer of tlie hands). A. Sticker has called attention to 

 several examples which indicate a causative relation of external 

 influences upon the establishment of cancer, as the occurrence of 

 skin cancer in cattle after branding (Mac Fadyan), and beneath the 

 chin in swine from chaffing (Eggeling). Possibly the frequence of 

 cancer of the anus of dogs has some connection with external inju- 

 ries (from the animal scraping the anal region along the ground, so- 

 called "sleigh-driving"). 



The origin of cancer should not, therefore, be attributed to any 

 one cause, as a definite cancer parasite or an infectious agent, but 

 may be determined from any influence (traumatic, chemical, infec- 

 tious) which occasions chronic inflammation and because of which, 

 as a result of the inflammatory process, an isolation of the living 



