IMMUNITY IN TUMOR TRANSPLANTATION 423 



was a somewhat greater variation as to the time of maximum increase. When 

 in rats and mice with growing homoiotransplanted tumors the period of obser- 

 vation was extended until the tumors had reached a considerable size and the 

 animals had become debilitated, the number of erythrocytes decreased and at 

 the same time the number of polymorphonuclear leucocytes increased in the 

 peripheral blood. A similar parallelism in the changes in erythrocytes and 

 leucocytes occurred in mice with growing autogenous (spontaneous) tumors. 

 There were no significant changes in the number and relative distribution of 

 lymphocytes and polymorphonuclear leucocytes until the tumors became moder- 

 ately large. From that time on there was a gradual increase in the total white 

 cell count and in the relative number of polymorphonuclear leucocytes. At the 

 same time a decrease in the total number of red cells and an increase in 

 reticulocytes occurred ; also, normoblasts appeared in the peripheral blood 

 when the later stages of the anemia were reached. When the tumors became 

 large, the average erythrocyte count fell to 4.12 million cells per cmm. 

 (Blumenthal). In the bone marrow the newformation of the red cells was 

 intensified and it appears probable that the increase in the number of poly- 

 morphonuclear leucocytes in the peripheral blood was caused by the stimula- 

 tion which occurred in the bone marrow as the result of the very marked 

 anemia. 



Heterotransplantation of rat and mouse tumors to guinea pig, mouse and 

 rat led in principle to the same changes as those observed after heterotrans- 

 plantation of normal tissues. There was an increase in polymorphonuclear 

 leucocytes in the peripheral blood, which set in between the second and fourth 

 day after transplantation and which reached a maximum between the sixth and 

 tenth day. It persisted somewhat longer than the increase observed after 

 heterotransplantation of normal tissues, but the degree of increase was about 

 the same in each. In each also the return of the number of polymorphonuclear 

 leucocytes to normal was followed by an increase in lymphocytes, which 

 reached a maximum usually between the sixteenth and eighteenth day after 

 transplantation and then dropped to the usual level. This rise in the number 

 of polymorphonuclear leucocytes following heterotransplantation of tumors 

 and of normal tissues was not associated with anemia and increased erythro- 

 poiesis in the bone marrow; it was presumably due to a direct effect of the 

 organismal differentials on the leucocytes or their precursor cells in the bone 

 marrow. 



If, twelve or twenty days following the homoiotransplantation of a piece of 

 normal tissue, a second homoiotransplantation of a similar piece is carried out, 

 a lymphocytic reaction follows also this transplantation as well, but in this 

 case the reaction occurs somewhat more rapidly, although the rise is not quite 

 so great in the majority of animals as after the first transplantation. The same 

 effect is obtained if in the first homoiotransplantation a piece of cancerous 

 tissue is used instead of normal tissue and if normal homoiogenous tissue is 

 then transplanted twenty days after the first transplantation. In principle, the 

 same results were obtained if two successive homoiotransplantations of 

 tumors were made; even if the second transplantation was delayed so long 



