most of the lymphatics pass by it on their course to the glands in the armpit. If a sore throat is the source of infection, the glands beneath the angle of the jaw enlarge. Thus various glands block the further progress of infection. In doing this their resources may be strained to the uttermost; they may enlarge, become tender, grow soft, fill with pus, break down and discharge the pus without the aid of a surgeon’s knife, although as soon as pus is recognizable within them it is wise to let it out. If germs pass through these first stations into the lymph-vessels beyond them, abscesses are formed in other situations. A condition of “blood-poisoning,” so called, is set up. The readiness with which leucocytes sacrifice themselves in their efforts to remove germs and decaying tissue is a matter of almost every-day experience. The fatty matter produced in the sebaceous glands of the skin normally overflows on to the surface. It serves to render the skin supple and impervious to water. Germs get into one of the sebaceous glands of the face or of the eyelid. The contents of the gland begin to decompose. Leucocytes enter it for the purpose of removing the putrescent substance. They lose their vitality and turn into pus corpuscles. The pimple or the stye bursts, and pus and fatty matter are discharged together. That the conversion of leucocytes into pus cells is due to want of oxygen has been shown by the following experiment: A minute piece of phosphorus is placed beneath the skin. Leucocytes gather round the spot with a view to removing the tissue which the phosphorus has destroyed. But phosphorus has so strong an affinity for oxygen that it exhausts the supply in the area of tissue which surrounds it. The leucocytes die before reaching the tissue immediately adjacent to the piece of phosphorus. Their dead bodies form round it a raised ring of pus cells. We can explain this readiness of leucocytes to sacrifice themselves in their efforts to reach foreign matter which needs to be removed, only by saying that the attraction of the food is greater than the repulsion of lymph destitute of oxygen. An amœba placed in comparable circumstances gives up the quest of food, however strongly chemiotaxic, and retreats towards water which contains oxygen sufficient to provide for its respiratory needs.