SOME CATALYTIC ASPECTS OF DISEASE AND DRUGS 233 



all that remains is some scattered oil-containing cysts lined with ordi- 

 nary epidermis. No real conversion into the neoplastic state has taken 

 place, though a second injection of dye at the same spot causes malig- 

 nancy to be simulated for a longer time. If the Scharlach R were not 

 lost, if it went along with the multiplying cells, increased as they did, 

 and because of this continued to urge them on, surely a growth run- 

 ning the course of a true neoplasm would result. Agents which do 

 precisely these things have been discovered. They are the tumor- 

 producing viruses." 



There is evidence showing that the viruses may often persist in cells 

 as harmless symbionts, ready to bring about disease when favorable 

 conditions permit. An example of these so-called "latent" viruses 

 occurs in the King Edward potato, where it causes no evident disease; 

 but it can kill other varieties upon inoculation. And a virus infec- 

 tion superimposed upon a "pre-cancerous" irritation may cause rapid 

 cancer development. Thus when the virus from the naturally occur- 

 ring papilliomas of wild cottontail rabbits is injected into the blood 

 stream of domestic rabbits already having papilliomas induced by tar, 

 "it localizes in these growths, which are benign and usually indolent, 

 with the result that some of them start growing with unprecedented 

 speed, while others change equal swiftness to carcinomas, often very 

 malignant, an alteration which tar papilliomas undergo only occa- 

 sionally and after a long while if let alone. It is plain that the virus 

 acts in concert with the unknown cause for tar tumors, with result in 

 cancers which otherwise would not occur." 37 It must here be pointed 

 out that the action of both the tar and the virus are explicable in 

 terms of persistent and heritable changes in biocatalysts; the virus 

 and/or its products may upset existing catalyst structures. 



In certain strains of mice most of the old females develop breast 

 cancers. If fathered by a male of a relatively "cancer-free" strain, 

 the young of a "cancer strain" mother develop cancers. But the 

 young of a "cancer-free" mother by a "cancer strain" father seldom 

 develop cancers. It was found by workers at the Roscoe B. Jackson 

 Memorial Laboratory at Bar Harbor, Maine, that in these cases 

 this "maternal influence" is not genetic, but is transmitted to the 

 sucklings by way of the milk. "So effective is the 'milk factor' 

 that a single nursing during the first days after birth is enough to 

 confer the liability to mammary tumors not only on the young 

 but on their descendants. Whatever it is that the milk contains 

 must get into the blood or lymph through the gut wall — which is 

 especially permeable to large molecules during the first days of 

 life — and be conveyed to the rudimentary mammary glands. 

 Here it persists and increases in quantity as the glands develop. 



