This is a monograph on the cerebrospinal fluid, with particular emphasis laid on the cytology. It is a critical monograph as well as a practical treatise. In it are incorporated also the personal observations of the author. In addition to the main data contained in the work there is a very extensive bibliography, covering 20 pages, which contains references not only to the French literature but also to a very considerable number of papers by American and English authors. The chief criticism of the book would be that in goodly part it is rather elementary. A great many pages are devoted to information which is available to the student or to the neophyte in the study of the cerebrospinal fluid in textbooks on the subject and which seems unnecessary in a book of this type.