THE UNIQUENESS OF THE INDIVIDUAL 



stant presence of, grow up with, these very substances, and so, 

 in the technical sense I have just explained, become tolerant of 

 what might otherwise have been their antigenic action. This 

 explanation sounds too facile to be true, but fortunately there 

 are certain exceptions which seem to prove the rule. Antibody- 

 forming cells obviously cannot become tolerant of any bodily 

 constituents which are formed, or do not become mature, until 

 the antibody-forming cells themselves have formed and become 

 mature; for example, they could not become tolerant of milk 

 protein or chemically distinctive ingredients of spermatozoa. 

 Nor could antibody-forming cells become tolerant of bodily 

 constituents which, however early they develop, are physio- 

 logically shut off from the remainder of the body, e.g. by lacking 

 a blood supply or lymphatic drainage; they should not therefore 

 become tolerant of the potentially antigenic action of the 

 characteristic proteins of the lens. If this interpretation is 

 correct, then substances like milk protein and lens protein and 

 spermatozoa should be capable of forming auto-antibodies, 

 though needless to say they never get a chance to do so in 

 ordinary life. So they are; appropriately administered, all can 

 form auto-antibodies in the body of which they themselves are 

 part. The phenomenon of tolerance is therefore of fundamental 

 importance in the mechanism by which the body learns to 

 discriminate between what is proper to itself and what is 

 foreign, and it is only under artificial or otherwise abnormal 

 circumstances that the mechanism of recognition goes wrong. 



6. CONCLUSION 



In this article I have shown how skin grafting can be used 

 for the detection and assay of individuality, whether in gold- 

 fish, mice or men. Although the inborn differences between 

 human beings are combinational in origin and inner structure 

 (they are not to be thought of as differences of either 'degree** 



184 



