210 Dr. Kussell. TJie Manifestation of Active [Mar. 15, 



It has been found that strain 63 is inhibited in its growth by the simul- 

 taneous inoculation of sarcoma 37, a tumour which renders mice resistant to 

 re-inoculation in a high percentage of cases. The percentage of success on 

 inoculation of strain 63 has been lowered from 100 down to 50, and even 25, 

 whilst in addition the rate of growth is greatly retarded as compared with 

 that in normal animals. 



The effect of a simultaneous inoculation of mouse embryo tissue upon 

 carcinoma 63 has also been studied, but an inhibition of the growth of the 

 tumours has not been observed. It suggests itself as a perfectly legitimate 

 explanation that the inefficacy of the simultaneous inoculation of embryonic 

 tissue to inhibit the growth of tumour 63 is due to the later development of 

 resistance after this treatment, and it may be a question of one or two days 

 only. By using tumour tissue to induce immunity, the immunity can be 

 brought to bear upon the inoculated tumour-tissue of carcinoma 63, before 

 the latter has had time to become fully established. This latter circum- 

 stance is of considerable importance, and has been demonstrated by extension 

 of these experiments to other tumour strains. Another carcinoma, strain 91, 

 has been used, but with this tumour it has not yet been possible to demon- 

 strate any inhibition where simultaneous inoculation with sarcoma 37 has 

 been performed. Apparently this tumour cannot be overtaken in its growth 

 by the concomitant immunity arising from the sarcoma, but continues to 

 develop quite as well in animals where the sarcoma is disappearing as it does 

 in the control series. 



The behaviour of tumour 63, however, demonstrates very clearly a case 

 where the immunity can overtake the early phases of growth and prevent 

 its continuation. This explanation further accords well with the histological 

 findings in early stages of grafts inoculated in immune animals. Briefly 

 stated, these led to the conclusion that the resistance was directed mainly 

 against the cancer cell's power of inducing a stroma reaction.* The experi- 

 ments next to be described support the above interpretation of the different 

 behaviour of strains 63 and 91. 



The treatment of mice by the inoculation of normal tissues of the mouse, 

 as described in these ' Proceedings/f has been found to prevent the develop- 

 ment of tumours implanted 10 to 20 days later, and the resistance evoked 

 by these normal tissues is of the same nature as the resistance evoked by 

 tumour tissue. The efficacy of this preliminary treatment stands out in 

 marked contrast with the disappointing nature of the results hitherto 



* Russell, B. R. G., " The Nature of Resistance to the Inoculation of Cancer," ' Third 

 Scientific Report of the Imperial Cancer Research Fund,' London, 1908, p. 341. 

 t Loc. cit., p. 209. 



