The value and duration of defence reactions of the skin to the primary lodgement of bacteria.

IN all animal infections there is a stage when the infecting microbes, taking advantage of a breach in the surface defences of the host, make their primary lodgement in or on the tissues. The fate of this primary lodgement-its suppres-sioIn or its persistence and growth into ani established infection- is determined in part by the antimicrobial properties of the tissues immnediately round it. Little, however, is of the efficiency of these tissue responses in the early stages of infection, of the part they play in nion-specific immunity, or of the physiological and pathological defects in the responses that determine the breakdown of natural resistances to the primary lodgement. Experimentally, it is obvious that suppres-sioni of this kind occurs when sub-infective doses of living pathogens are injected; and in nature they may justifiably be assumed to occur as part of the means whereby animals remain healthy in spite of the substantial microbial hazards of their enivironmenit. Other tech niques, of ex)eriments inci(Iental to the main inivestigation, are described in the appropriate sections.