1910.] Reactions to the Implantation of Cancer, etc. 297 



treated with skin ground at a temperature of about 0° C. gave 10 tumours in 

 11 mice, i.e. 91 per cent., and these tumours grew more rapidly than the 

 control tumours. This experiment demonstrates that an efficient disinte- 

 gration of the cells of normal tissues robs them of all immunising properties. 

 We have later repeated this experiment with other normal tissues, spleen, 

 liver, and blood, with the same result. 



Another method for obtaining the proteids of the cells has been tried : 

 that of obtaining the press-fluid from tumours and normal tissues by Buchner's 

 press after disintegration of the cells by grinding in a mortar with sand. 

 The effect of a preliminary inoculation of such press-fluid on a subse- 

 quent inoculation of cancer was studied. Injection of 0'50 c.c. of tumour 

 press-fluid, 11 days previous to testing inoculation, far from having any 

 immunising effect, on the contrary hypersensitises the animals. 



These experiments with ground material and press-fluid, both of cancerous 

 and normal tissues, show that the power of inducing resistance is not bound 

 up with the proteid of the cell as a chemical entity, but in some way or 

 other depends upon properties of the living cells. 



The investigations described above refer especially to mechanically disin- 

 tegrated cells, but the results also apply to disintegration by autolysis, by 

 heat, and to the influence of radium. In this latter case the microscopical 

 appearance of the cells and their anatomical structure remains apparently 

 unaltered. This shows that the loss of immunising power is not bound to 

 any special form of disintegration, but is common to all means by which the 

 life of the cell is destroyed. 



The conclusions are : — 



Complete disintegration of the tumour cells robs them entirely of their 

 immunising properties. 



There is no difference between tumour cells and normal cells in this 

 respect. 



The absence of immunising power does not seem to be a question of dose 

 of introduced material, .because relatively enormous doses of dead material 

 {c.(j. 1/26 of the weight of the animal) do not induce any resistance, whereas 

 minimal doses of living cells (c.//. 1/1300 of the weight of the animal) have 

 this effect. 



The immunising property is not bound up with the protein of the cell, but 

 depends on a different principle. Living cells are necessary to induce resist- 

 ance to transplantation of cancer. It seems necessary that these cells must 

 not only remain alive, but also even grow for a certain time ; without the 

 fulfilment of these conditions the reaction inducing active resistance is not 

 set up. 



VOL. LXXXII. — B. 2 A 



