Like a boil reemerging after years in remission, like a pestilence of locusts descending from a clear blue sky, like a bad odor coming up from the waste treatment plant across the river now that winter is fading, mergers and acquisitions are back. Perhaps I'm being a trifle negative. M&A fulfills important functions in the business cosmos, much the way arachnids keep the world safe from overpopulation by mosquitoes. Certainly, some people must benefit from the mindless, heedless, often doomed merging of two entities.