888 CHEMOTHERAPY 



organotropic substances. Here, of course, the difficulties are great, 

 because the structural, biologic, and functional differences between the 

 normal cell and the cancer cell may be slight, and substances must be 

 found that possess a high affinity for the cancer-cell only. 



That this condition may indeed exist has been indicated by the experi- 

 ments of Wassermann and his collaborators. These investigations 

 were based upon the discovery, by Gosio, that sodium selenate and so- 

 dium tellurate are more rapidly reduced by cancer-cells than by normal 

 cells, and that this reduction takes place within the bodies of the cells. 

 Experiments on mouse tumors showed that the injection of these sub- 

 stances into the growths may actually lead to their destruction, the 

 explanation, according to Neuberg and Caspani, being that certain 

 compounds of the heavy metals in colloidal form favor self-digestion 

 (autolysis) of the tumor cells. 



The problem now resolved itself into finding some substance that 

 would carry the metals to the tumors, or, as Wassermann said, "the 

 building of rails which would reach the tumor and by which the selenium 

 could travel," as local injection was obviously out of the question from 

 the practical standpoint. Eosin, being a substance endowed with great 

 powers of diffusion, was selected for the purpose, and a number of eosin- 

 selenium compounds were tried out. The results were encouraging, as 

 in a number of instances the tumors became soft and sloughed away or 

 their further growth was checked. "If three consecutive daily intrave- 

 nous injections of the eosin-selenium compound are given in 2.5 gin. doses 

 for 15-gram mice, a distinct softening and elasticity of the tumor are 

 noticed on the fourth day; on the fifth day a fourth injection of the 

 same dose is given, after which there is no longer the feeling of a solid 

 tumor, but rather that of a fluctuating cyst in which small, movable 

 tumor particles can be discovered. After the fifth injection on the 

 seventh day this soft mass becomes smaller, the capsule becomes lax, 

 and the configuration of a circumscribed tumor can no longer be dis- 

 tinguished, but only a long edematous cord can be felt. Usually, as a 

 result of the sixth injection, in favorable cases, the absorption and 

 diminution proceed so that one gets the feeling of an empty sac. In 

 ease no intercurrent disease occurs, the animal is cured in about ten 

 days, with a disappearance of all remnants of the tumor." 



As these results were observed after intravenous injection of the 

 mixtures, and as no injury to the body-cells was apparent, it seems that a 

 step forward has really been taken; at least, these investigators have 

 shown that it is possible for chemical substances to pass from the blood 

 and attack tumor cells. Copper and tin have been found to possess a 



