THE UNIQUENESS OF THE INDIVIDUAL 



uneasily upon the significance of their physical and chemical 

 properties; but the only way to be sure that they are still in 

 working order is to see if they can still discharge some genetic- 

 ally specific function. The study of nucleic acids was in the 

 same condition, all dressed up and nowhere to go, until the 

 development of Griffith's great discovery of bacterial trans- 

 formation. It is to be hoped that skin grafting will do as much 

 for nucleoproteins, for in studying the antigenic activity of 

 homografts we are studying a proximate genetic property, and 

 it is very likely that anything which destroys the power of a 

 nucleoprotein to act as an antigen in transplantation im- 

 munity will also destroy its genetic competence, i.e. the pro- 

 perties which empower it to direct the course of development 

 along certain exactly specific lines. 



The third implication has not yet shaped itself into any- 

 thing solid enough to be called an opinion; it is still in the 

 gestation period of conscious thought, a state of querulous 

 unease. In Section 5 of this article I shall give reasons for 

 believing that antigenic substances of the kind that cause 

 transplantation immunity are constantly manufactured and 

 emitted during the everyday life of ordinary living cells. They 

 give no evidence of their presence or activity until the tissues 

 which manufacture them are grafted upon an individual to 

 whom they do not belong. They then act as antigens, setting in 

 train a reaction which causes their source, the grafted tissue, 

 to be destroyed. What then is the normal function of these 

 substances which act as antigens in the entirely artificial 

 context provided by grafting? There is every reason to believe 

 that all the nucleated cells of the body give forth these nuclear 

 particles, each carrying the genetic hall-mark of the individual, 

 and that they enter the lymphatics and in due course reach the 

 regional nodes. What, if anything, do they do? 



It may be said at once that although the continued life of 

 the cell may well depend on the continual emission of nucleai 



166 



