Of the various hydrocarbons known to possess cancer-producing properties, the most potent are methylcholanthrene and cholanthrene (Qa In the regularity and rapidity with which they produce tumors in experimental mice these substances so far outshadow all of the many other derivatives of lJ2-benzanthracene thus far investigated (largely by Cook and co- workers2) that it is a matter of considerable interest to attempt to define the features of ...