574 Crown Gall-Animal Cancer Analogy 



they demonstrated indubitably that the filtrate of the crushed 

 cells will cause the disease, and a little later that the virus persists 

 in cells killed by freezing, by heat, by drying, and by glycerin." "^ 

 Even today, this presumably " " living organism,' " ultramicro- 

 scopic in some, perhaps all, of its forms, an organism having 

 specific attributes or properties, distinguishable from ferments, 

 and practically as capable of inducing chicken tumors as the car- 

 cinogenic hydrocarbons, can survive physical cell destruction, and 

 yet it has not been isolated and cultivated in pure cultures in vitro 

 as well as in vivo. Very important research has been performed 

 in recent years on this virus-like agent of chicken tumor. At a 

 meeting of the American Philosophical Society on April 19, 1912, 

 Rous read a paper on "An avian tumor in its relation to the tumor 

 problem." ^-- Smith may have attended this meeting, although 

 not yet a member of the Society, and, much enthused, sent Rous 

 his letter of May 16 quoted in Chapter IX. In his address " Twen- 

 tieth Century Advances in Cancer Research," he quoted from Rous' 

 paper several times. Much more could be said about these inves- 

 tigations started at the Rockefeller Institute for Medical Research 

 but one more point has special pertinence. With the use of cell- 

 free filtrates and under definite, highly artificial conditions, the 

 disease can be transmitted from one animal to another, although 

 under natural conditions, it has not been found transmissible; that 

 is, healthy fowls may be kept with diseased chicken without 

 danger of infection. 



Fibiger supplied Smith with the ten photomicrographs of rat 

 Spiroptera cancer used to illustrate his discussion of the Dane's 

 '"' rat carcinoma due to cockroach-nematodes." Later Fibiser men- 

 tioned Smith's " renowned researches " in a lecture before the 

 Danish Medical Association. Several letters passed between the 

 two scientists during 1922-1924. On November 1, 1922, Fibiger 

 wrote: 



I have published during the last years no special papers concerning the 

 nematode-carcinoma, but in various papers I have mentioned the summary 

 of the results. I am sending you these papers accompanied with some 

 papers concerning the tar carcinoma. Having given away during these last 

 years an exceedingly great number of preparations, I amsorry to say that just 



^-^Idem, 301. 



'^"^ Proc. Amer. Philos. Soc. 51: 201-205; also, xi, minutes of the meeting. 



