Since 1916 several important contributions to the study of neurosyphilis have appeared in the German literature. These have been based in part on studies of spirochetes made possible by Jahnel's1 modification of the method of silver impregnation. Little, if any, reference has been made to these contributions in our American literature. This is probably due to the failure of the periodicals to reach the United States, and to failure or delay in indexing. It is hoped that by here presenting Jahnel's method it will be more accessible and better appreciated. Comment, such as is justified by a short acquaintance with, and use of, the method, will be made.
Similarly the recently published cover-glass method of Warthin and Starry2 will be referred to.
JAHNEL'S METHOD
The failure of foreign workers to obtain satisfactorily constant results with existing silver impregnation methods in nervous tissue led Jahnel to evolve his method.