162 ON VARIABILITY AND ADAPTATION 



the extreme. It is only those variations (and mutations) induced, 

 not in one, but in several members of a species by subjection to 

 a common alteration in their environment, which with gamo- 

 genesis become progressively more pronounced and are of 

 evolutionary value.] 



It will be seen that the picture of inflammation here given is 

 very different from the old view in which the dominating idea 

 was that inflammation is essentially an injurious process leading 

 to cell — and tissue — destruction. Here we regard the irritant as 

 capable of causing cell and tissue destruction, and so long as 

 the irritant is in action so long may this destruction continue. 

 But inflammation itself we regard as the series and sum of the 

 reactive processes set up in the tissues, and then bringing about, 

 not destruction, but the very reverse. Taking as our definition 

 that inflammation is the response or reaction to injury, we are 

 inevitably led to see that this response results in counteracting, 

 or more exactly in tending to counteract, the deleterious effects 

 of the irritant ; the inflammatory process tends towards repair. 

 It may not result in repair, for, as we have pointed out in several 

 instances, too often the reaction is either inadequate or excessive. 

 The exudation may possess but slight bactericidal powers, or 

 may be poured out in such quantities that the microbic irritant, 

 instead of being retained in the region of injury, is conveyed 

 outside that region ; the wandering cells, instead of destroying, 

 may undergo destruction ; they may incorporate bacteria, but 

 not be able to annihilate them ; the fixed cells may either form 

 an incomplete cicatrix, or continue to proliferate in excess. 

 Attempt at repair is not repair. Notwithstanding, studying the 

 various factors involved, it is forced more and more upon us 

 that each tends in one definite direction, and the sum of the 

 processes is reparative. 



This conception of the process of inflammation has met with 

 considerable opposition. It is urged that to consider inflamma- 

 tion as an attempt at repair is teleological, i.e. is to assume that 

 each reaction in the process is, in itself, purposeful. And, 

 carrying this objection to its ultimate end, "you conceive," 

 say the critics, " that the leucocyte is endowed with intelligence 

 so that it recognizes in the microbe a foe to the organism ; scents 

 it from afar ; hunts, seizes, and digests it, and then, its duty 



