The competitive exclusion principle.

because of a belief that it is best to use that wording which is least likely to hide the fact that we still do not comprehend the exact limits of the principle. For the present, I think the 6'threat of clarity" (3) is a serious one that is best miniInized by using a formulation that is admittedly unclear; thus can we keep in the forefront of our minds the unfinished work before us. The wording given has, I think, another point of superiority in that it seems brutal and dogmatic. By emphasizing the very aspects that might result in our denial of them were they less plain we can keep the principle explicitly present in our minds untit we see if its implications are, or are noty as unpleasant as our subconscious might suppose. The meaning of these somewhat cryptic remarks should be come clear further on iIl the discussion. What does the exclusion principle mean? Itoughly this: that (i) if two noninterbreeding populations "do the same thing"-that is, occupy precisely the same ecological niche in Elton's sense (4)-and (ii) if they are "sympatric"that is, if they occupy the same geographic territory-and (iii) if population A multiplies even the least bit faster than population B, then ultimately A will completely displace B, which will become extinct. This is the 44weak form' of the principle. A1ways in practice a stronger form is used, based on the removal of the hypothetical character of condition (iii). We do this because we adhere to what may be caIled the axiom of inequality, which states that no two things or processes