This is essentially a laboratory book, which gives the technique of practical bacteriologic study. The life history of the commoner bacteria is taken up and the different steps of their development shown and the directions for their complete demonstration are minute and accurate. It is not a treatise on bacteriology, but as its title indicates, a working guide. The formulæ for staining fluids and culture media are given in extenso. The blank pages will enable the worker to make full notes of his own experiments.