Here, then, we have this little bunch of idle tissue, about the size of a small hazelnut, ready for any mischief which our Satan-bacilli may find for its hands to do. A child kept in a badly ventilated room inhales into his nostrils irritating dust or gases, or, more commonly yet, the floating germs of some one or more of those dozen mild infections which we term "a common cold." Instantly irritation and swelling are set up in the exquisitely elastic tissues of the nostrils, thick, sticky mucous, instead of the normal watery secretion, is poured out, the child begins to sneeze and snuffle and "run at the nose," and either the bacteria are carried directly to this danger sponge, right at the back of the nostrils, or the inflammation gradually spreads to it. The mucous membrane and tissues of the nose have an abundance of vitality,--like most hard workers,--and usually react, overwhelm, and destroy the invading germs, and recover from the attack; but the useless and half-dead tissue of the pharyngeal tonsil has much less power of recuperation, and it smoulders and inflames, though ultimately, perhaps, it may swing round to recovery. Often, however, a new cold will be caught before this has fully occurred, and then another one a month or so later, until finally we get a chronically thickened, inflamed, and enlarged condition of this interesting, but troublesome, body. What its capabilities are in this respect may be gathered from the fact that, while normally of the size of a small hazelnut, it is no uncommon thing to find a mass which absolutely blocks up the whole of the upper part of the pharynx, and may vary from the size of a robin's egg to that of a large English walnut, or even a small hen's egg, according to the age of the child and the size of the throat. Dirt has been defined as "matter out of place," and the pharyngeal tonsil is an excellent illustration. Nature is said never to make mistakes, but she is apt to be absent-minded at times, and we are tracing now not a few of the troubles that our flesh is heir to, to little oversights of hers--scraps of inflammable material left lying about among the cogs of the body-machine, such as the appendix, the gall-bladder, the wisdom teeth, and the tonsils. One day a spark drops on them, or they get too near a bearing or a "hot-box," and, in a flash, the whole machine is in a blaze.