VI INTRODUCTION 



only after a long lapse of years by Pasteur. On the heels of the latter 

 there appeared at once, and has since then followed, an army of men 

 whose names crowd the history of the subject, and which many of these 

 are bound permanently to adorn. The old vague theories of infection 

 have taken form, and to observed facts has been added productive 

 theory. The great danger attending this luxurious development is that, 

 temporarily at least, the simpler, and perhaps the more obvious, facts 

 are likely to be neglected; and, also, that symbolization by theories 

 elaborated to harmonize with discovered facts will be accepted too fully 

 as explanatory when in reality it does not explain, and that, as a result, 

 investigation will finally be hampered instead of aided. In the almost 

 universal drift of experimental studies to internal stereochemical factors, 

 are we not in danger of placing too little stress upon actual and possible 

 physical factors? Is there no danger that, by failing to lay stress upon 

 the obvious importance of the turbinate mechanism in the nose as a 

 natural anatomic factor, our rhinologists may at least feel justified in 

 sacrificing this mechanism too readily for what may be but trivial local 

 reasons? Can we insist that every phenomenon described with facility 

 in terms of the side-chain theory is really a manifestation of chemism, 

 when perhaps, with added investigation along lines of physical absorp- 

 tion and the physical properties of colloids, an equally satisfying con- 

 ception may be had, and possibly new facts be developed? Are we not 

 blundering in rushing madly after matters of specificity as determined 

 by antigen, when perhaps in reality we are confronted by potential and 

 kinetic modifications due to peculiarities of diet or environmental cir- 

 cumstances? The verity of phagocytosis is open to proof by observa- 

 tion, and its variations are likewise to be demonstrated. Is the explana- 

 tion of opsonins so convincing that merely the word itself is enough to 

 satisfy the investigator? 



Infection and immunity constitute a definite chapter in pathologic 

 science. The processes lack the dignity of a separate science only in 

 that they present variations, and the fact that these are glossed over by 

 brilliant theories and conceptions cannot prevent the deliberate recogni- 

 tion of serious incompleteness. Yet this criticism can be applied to the 

 growth of every branch of scientific knowledge. It in no wise militates 

 against the right and the need for setting forth the subject in the light 

 that, for the time, is afforded it. The importance of the criticism lies 

 only in its acknowledgment, lest the subject as at present understood 

 be accepted as fixed. With this danger obviated, and with all theories 

 accepted for the time only as working theories, and their adoption not 



