A great deal of activity has lately been exhibited in so-called dairy bacteriology, and a long list has already been compiled of milk, cheese, and butter microbes; and agricultural authorities, even in this country, are slowly awakening to the fact that, in order to compete on modern lines with foreign dairy produce, dairy schools must be established, where bacteriology is taught, and where instruction is given in the principles of scientific butter and cheese making. But bacteria of the brewery and of the dairy are not the only useful germs which are to be found on the shelves of microbe museums. Wine and tobacco manufacturers on application may respectively obtain the bacterial means of transforming the crudest must into the costliest claret, and the coarsest tobacco into the most fragrant Havana. Already considerable progress has been made in the isolation of particular varieties of wine-yeast, whilst highly encouraging results have been obtained by Suchsland and others in the separation of various valuable tobacco-fermenting organisms. Agricultural authorities, again, owe a debt of gratitude to those distinguished investigators whose labours have discovered the art of imprisoning the micro-organisms which play such an important part in the fertilisation of the soil. Bacterial fertilisers are amongst the latest achievements which bacteriology has accomplished in this wonderful half-century, and the purchase of special varieties of bacteria to suit the requirements of particular kinds of leguminous plants is now fast becoming a mere everyday commercial transaction. But efforts for the amelioration of the conditions under which plant life is carried on have not been confined to providing plants with suitable bacterial friends; vigorous and successful efforts have been made to remove from their _entourage_ those bacterial enemies and undesirable parasites which have for so long played so important a part in the crop-returns of many an agriculturist.