We will begin with their most frequent and most serious injurious effect, though not the earliest,--the impairment of the child's power of attention and intelligence. So well known is their effect in this respect that there is scarcely an intelligent and progressive teacher nowadays who is not thoroughly posted on adenoids. Some of them will make a snap diagnosis as promptly and almost as accurately as a physician; and when once they suspect their presence, they will leave no stone unturned to secure an examination of the child by a competent physician, and the removal of the growths, if present. They consider it a waste of time to endeavor to teach a child weighted with this handicap. How keenly awake they are to their importance is typified by the remark of a prominent educator five or six years ago:-- "When I hear a teacher say that a child is stupid, my first instinctive conclusion is either that the child has adenoids, or that the teacher is incompetent." The lion's share of their influence upon the child's intelligence is brought about in a somewhat unexpected and even surprising manner, and that is by the _effects of the growths upon his hearing_. You will recall that this third tonsil was situated at the highest point in the roof of the pharynx, or back of the throat. The first effect of its enlargement is naturally to block the posterior opening of the nostrils. But it has another most serious vantage-ground for harm in its peculiar position. Only about three-fourths of an inch below it upon either side open the mouths of the Eustachian tubes, the little funnels which carry air from the throat out into the drum-cavity of the ear. You have frequently had practical demonstrations of their existence, by the well-known sensation, when blowing your nose vigorously, of feeling something go "pop" in the ear. This sensation was simply due to a bubble of air being driven out through this tube from the back of the throat, under pressure brought to bear in blowing the nose. The luckless position of the third tonsil could hardly have been better planned if it had been devised for the special purpose of setting up trouble in the mouths of these Eustachian tubes. Just as soon as the enlargements become chronic, they pour out a thick mucous secretion, which quickly becomes purulent, or, in the vernacular, "matter." This trickles down on both sides of the throat, and drains right into the open mouth of the Eustachian tube. Not only so, but these Eustachian tubes are the remains of the first gill-slits of embryonic life, and, like all other gill-slits, have a little mass of this same lymphoid or tonsilar tissue surrounding them. This also becomes infected and inflamed, clogs the opening, and one fatal day the inflammation shoots out along the tube, and the child develops an attack of earache. At least two-thirds of all cases of earache, and, indeed, five-sixths of all cases of deafness in children, are due to adenoids.