This mongraph upon spirochetes by Doctor Collier of Buenos Aires is Part II, Vol. III, of the Handbuch der biologischen Arbeitsmethoden, published by the well known Berlin firm—Urban & Schwarzenberg. The work is an excellent summary of all that we know at present regarding the methods of examining, culturing and staining the spirochetes, together with the technique used in animal experimentation. It is a useful compendium of our knowledge regarding the subject and includes not only much that is new, but also all of the old technical methods that have proven reliable. It is refreshing to note that the author quotes English and American authorities quite widely, something which we regret to note is not always done by German writers of the present day. This work should prove most useful to all physicians who are interested in the subject of the relation of spirochetes to disease, and to technicians who have to do with these organisms in the laboratory.