A cautionary but reassuring note to the reader: this subject, chosen by the mysterious B.M. (I now believe the meaning behind the moniker is less than savory), while generally understood to be offensive, may be approached in such a way as to render it harmless. I wish to remind you that I am, after all, a medical doctor and possess all the faculties and sensibilities therein. I mean to say that I will treat this affair in a delicate and professional manner befitting a gentleman of my standing. The reader may think of this as an educational opportunity--and one ought not dismiss an occasion to learn, especially if it be in one of the higher arts, such as medicine, philosophy, or law. But let us exit the preamble and move straight to the point.

The Latin word flatus means "wind", or "blowing", from the verb "flare", meaning "to blow", and during the reign of that language it was equally as likely to indicate one's breath as it was to indicate the airy expulsions of the nethermost regions of the abdomen. Coincidental adjunct: it is proof of History's sense of humor that the Latin word "flare" should be identical in spelling to the contemporary English word "flare", an incendiary device which might be utilized by intoxicated scholars in the creation of "the flatus lightning". I have served more than one patient who, having imbibed an amount of alcohol exceeding that which is humanly prudent, attempted the ignition of their own flatus and caused themselves bodily harm and, in some cases, loss of hair. I treated individuals who have borne witness to such acts and not come away unmarred. I have even heard tales of an especially hirsute gentleman against whom nature and the fates conspired. As the legend has it, the man, who suffered from that cruel disease known today as Hypertrichosis, had just returned from gorging himself at a day-long Summer feast. He was exceedingly warm and, being a bachelor, removed his clothing and reclined in his favorite chair, seated near the hearth. Apparently, some spark remained in the hearth from the previous nights fire, and when this hairy naked ape let loose, he was instantly set ablaze, poor sod.

Leaving etymology and myth, we find that the flatus in humans has three main causes. First and most common, gases are produced during the chemical breakdown of foods. Some foods produce greater quantities than others. Second, an individual may swallow air. This trapped air may be released as a fit of hiccoughs, or may work its way down to the intestines. And finally, gases are often produced by microscopic organisms residing in the digestive tract. These may be simple bacteria or yeasts, or in some cases the more unusual microbes called methanogens. Commonly found in ruminants, but less so in humans, these creatures produce methane as a by-product of respiration, a process known as methanogenesis.

As to the nature and composition of the flatus, you may be surprised to discover that its primary ingredients are all completely odorless, those being Nitrogen, Hydrogen, Carbon Dioxide, Oxygen, and Methane. Yes, sirs and ladies, Methane is an odorless gas, contrary to popular misconception. That rank and foul stench which you may have experienced or produced, that evil effluvium, that poison perfume, is caused by a separate component, or host of components, featuring sulfuric molecules which are produced by the breakdown of proteins. For this reason, vegetarians are likely to produce gas more frequently, but with less odor, while those who consume meat and dairy will produce gas less frequently, but with greater pungency. Shinta Cho's great treatise on the subject, "The Gas We Pass", explains this concept to accompanying paintings of zoo keepers covering their noses and wrinkling their brows. It has also been suggested that a similar process may affect the flavor of a gentleman's onanic expulsions, but I have been unable to find scientific research in this area.

And that concludes our lesson for today. But you should remember, dear readers: Laugh and the world laughs with you; fart and they'll stop laughing.