The Atlas is unique in the field of cytologic diagnosis for completeness, excellence of illustrations, and combination of both theoretical and practical aspects of the subject. Supplement I increased its value to pathologists by correlating histopathologic and cytologic findings. Supplement II continues the plan, adding many new cases of benign and malignant tumors. It includes a plate showing malignant cells found in the spinal fluid, three plates showing malignant cells found in the circulating blood, and a chapter on recent observations in this field.