IMMUNITY AND THE POWER OF DIGESTION. 2O3 



A most wonderful property exhibited by the tissues themselves 

 is to inhibit growth of foreign tissue. This resistance of the 

 organism against proliferation of any heterogeneous cellular 

 elements, be it normal tissues, tumor cells or microorganisms, is 

 more generally known under the term of immunity. There is 

 little need to emphasize the importance of any new information 

 concerning this problem. Disregarding, however, the most earn- 

 est efforts and attempts to throw upon this property light suffi- 

 cient to master it, no definitive knowledge has yet been acquired 

 concerning the nature of this property. 



In all organisms, plants and animals as well, the power of 

 resistance against proliferation of any foreign tissue does not 

 seem to depend upon the activity of a special organ in the 

 organism. A graft of heterogeneous tissue simply does not 

 take, a tumor graft does not grow, microorganisms do not pro- 

 liferate, die and disappear in an immune or immunized animal. 

 A living cell endowed with the faculty of proliferation, for ex- 

 ample, a tumor cell, well known for its high rate of proliferation 

 and on account of this property disastrous to the organism, on 

 which it has settled, if grafted on an immune organism, will 

 certainly find here all of the elements needed for the building 

 up of its own protoplasm, for we know that the tissues of the 

 organism are abundantly provided with various amino-acids, 

 and these not being specific, can be used equally well by any 

 tissue. And still a tumor cell will not live on an immune organ- 

 ism. It dies and disappears. 



If now we inquire into the relation between the digestive power 

 of the cell and resistance in a unicellular organism, we will 

 see that both phenomena in this case are very closely connected. 

 A unicellular organism can ingest another living organism, bac- 

 teria as well and the latter, while within a cytoplasmic vacuole of 

 the former, are killed and consecutively digested by the enzymes 

 of the phagocyte. The unicellular organism in this case proves 

 to be immune against a possible intracytoplasmic proliferation 

 of the ingested living individual, primarily and solely because 

 of its digestive capacity. 



The question whether in a multicellular organism any relation 

 exists between its resistance against proliferation of a foreign 

 tissue in it and a digestive power of its tissues is obscured by the 



