Book reviews

Dr. Coles is already well known by his book on the examination of the blood, and we do not doubt that his new manual will prove as serviceable as its predecessor. In it, ample guidance will be found by those desirous of carrying out bacteriological investigations for diagnostic purposes; the methods described being such as require no laboratory for their performance, any practitioner who can afford the time necessary for the work will find the detailed instructions given sufficient to enable him to differentiate any of the common pathogenic micro-organisms. Serum and cyto-diagnosis are also shortly dealt with. The feature, however, which will probably do most to give the book permanent value is the account of the author's researches on acid-fast bacilli, and the criteria which he lays down for distinguishing the bacillus tuberculosis from the smegma and other acid-fast "pseudo-tubercle" bacilli. His observations prove the ordinary statement that alcohol affords a ready means of distinguishing between these to be fallacious. If, as he hopes, the method of decolorisation which he advises (Pappenheim's solution for from four to twelve hours) enables the question whether a particular organism (in milk, for example) is, or is not, tubercle, to be settled without resort to inoculation and its attendant delay, bacteriologists will be greatly in Dr. Coles' debt.