1910.] Resistance to Implantation of Malignant New Growthti. 303 



graft. After two to three days there was scarcely a single cancer cell left, 

 whilst the surrounding rat tissues were proliferating actively and invading 

 the dying graft. Here one had to deal with an active immunity against 

 a foreign protein, and not with an immunity against a cancer cell as such. 

 In spite of the observations made and recorded at that time, von Dungern 

 and Coca (11) have since compared a similar phenomenon with the immunity 

 against cancer from which it is so totally different, and have built up an 

 hypothesis of " allergetic " immunity against cancer. They performed their 

 immunity experiments with an epidemically occurring fibrocellular growth 

 of the hare, which they have succeeded in transferring through eight 

 generations in a strange species, viz., in rabbits. They find that when 

 a rabbit has been successfully inoculated with this growth, it is impossible 

 to obtain success with a re-inoculation. The site of re-inoculation is 

 frequently the seat of a marked oedema, and they have found by histological 

 e.xaminatiou of the site two or more days later, that there is extensive 

 reaction witli production of large mononuclear cells which are specially 

 abundant in the veins and capillaries. They regard this reaction as being 

 evidence of a tissue immunity, and especially of the nature of a local 

 hypers'ensibility, in that the tissues having been once exposed to the action 

 of these foreign cells, they react more energetically to second inoculation of 

 tliern, apparently as the rat tissues have been described to do to re-inocula- 

 tion of mou.se tumour. Von Dungern and Coca have not made the direct 

 observation that, in transferring this hare tumour to rabbits, they have been 

 effecting a transplantation. If we accept their view, based upon indirect 

 observations, that the transference of this tumour is really a transplantation, 

 then their immunity results are comparable to those obtained in rats when 

 inoculated with mouse tumour, with this difference, that it has been possible 

 to propagate the hare tumour through several generations of rabbits. In 

 a recent publication, von Dungern and Hirschfeld (12) claim that this local 

 allergetic reaction is of great importance in its bearings on immunity to 

 cancer. 



The following experiments show how very different is the nature of the 

 immunity produced by inoculating cancer of a strange species from the 

 resistance to cancer produced by the absorption of tumour or normal tissues 

 of the same species. In these experiments the behaviour of tumour- 

 strain " 199 " has been studied in the rat. When 0"2 c.c. of this tumour is 

 inoculated into rats, tumours 2 to 3 cm. long by 0'5 to 0"75 cm. broad are 

 obtained in from eight to ten days. Histological examination of these 

 tumours at about the eighth or ninth day has shown them to be composed 

 almost entirely of granulation tissue, which in the rat is mainly fibroblastic 



