FURTHI-R RlZSEARCHI-S IN DlSIIASHS Ol PLANTS ^27 



plants, and he olTercd experimental data tending to establish that 

 oxvi^en hunger followed by increased acidity in the tissues of 

 plants could, in the absence of parasites, result in turnors. " I hope 

 to convince you, " he uri;ed, that tumors may be also due " to a 

 lack of aeration and the resulting increase in acidity of the imper- 

 fectly aerated tissues." '- He described four series of experiments 

 " following out [his] theory that disturbed cell respiration is at 

 the bottom of tumor formation . . . results [obtained] in the 

 absence of parasites by limiting the intake of air in various ways, 

 and in each experiment [he reached] the same result — increased 

 acidity of tissues and the production of small hyperplasias." A 

 point of distinction followed.^'' 



In crown gall, and various other tumors due to parasites the parasite 

 furnishes the acids and other stumuli as a direct result of its metabolism, 

 but the small benign tumors I am describing arc not the result of para- 

 sitism. The increased acidity probably results from the incomplete com- 

 bustion of carbohydrates, i. e., from anaerobic cell-respiration due to poor 

 circulation and imperfect aeration, which we know to be a peculiarity ot 

 tumors in general, since most of them are poorly vascularized and out of 

 the general circulation. 



If, for any reason, conditions such as I have outlined should occur in 

 parts of the animal body, I should expect to see similar phenomena arise 

 in such parts and, the nutrition being more abundant, the tumors might 

 become large. 



This paper, though resulting from his studies of crown gall and 

 the general phenomena of tumor formation, treated " the experi- 

 mental production of small benign tumors," their developmental 

 physiology and morphology. Crown gall tumors and animal 

 malignancies were considered, but his references to the problem 

 of human cancer were few. At one point, concluding a paragraph 

 about the plant cancer, crown gall, he said: " Like cancer, if taken 

 early, the tumor may be removed completely; but in later stages 

 of growth it often returns after removal." He summarized his 

 address thus: 



I have produced hyperplasia (1 ) by the direct application of dilute acids 

 and alkalies to susceptible plant tissues; (2) by the introduction into the 

 tissues of certain foreign organisms (especially the crown gall bacterium 



^^ Production of tumors in the absence of parasites. Arch, of Derm, and Syph., 

 op. ch., reprint, 1. 

 ^" Idem, 5, 6. 



