A simple, well constructed bacteriological incubator GAGE--The Microscope An Introduction to Microscopic Methods and to Histology By SIMON H. GAGE. Twelfth Edition. Entirely rewritten, and with many new illustrations. Price, postpaid, $3.00. This work aims to give help to everyone who uses the microscope, whether he is a beginner or an advanced worker. COMSTOCK--A Manual for the Study of Insects By JOHN HENRY COMSTOCK, Professor of Entomology in Cornell University, and ANNA BOTSFORD COMSTOCK, member of the Society of American Wood-Engravers. 8vo. cloth, IX. +701 pages, 797 figures in the text, and six full page plates. Nearly all of the figures were engraved especially for this work. Postpaid $4.07; net $3.75. This hand-book is designed to meet the needs of teachers in the public schools and of students in high schools and colleges. NEEDHAM--General Biology A book of outlines and practical studies for the general student By JAMES G. NEEDHAM, Professor of Limnology and General Biology in Cornell University. Cloth 8vo. XIV. +542 pages; 288 figures, mostly original. Postpaid $2.00. This book is expressly designed to help the general student obtain a comprehensive grasp of the principles of biology. NEEDHAM & LLOYD--The Life of Inland Waters A Text-Book of Freshwater Biology By JAMES G. NEEDHAM, Ph.D., Professor of Limnology and General Biology in Cornell University, and JOHN T. LLOYD, A.B., Assistant in Limnology in Cornell University. This book is a broad presentation of the field of fresh-water biology, primarily in its scientific aspects, also in its relation to commercial, civic, aesthetic and public health interests of man. There is no book in the English language covering the field. Copiously illustrated with photographs from Nature. 438 pages; 244 figures. Price $3.00. GAGE--Optic Projection By SIMON HENRY GAGE, Professor Emeritus of Histology and Embryology in Cornell University, and Henry Phelps Gage, Ph.D. This work of over 700 pages and with over 400 figures is of especial interest to workers in all fields of Biology in that it deals especially with the use of the Projection Microscope for demonstrations and for drawing. It also gives the fundamental principles of all the forms of projection. A 16-page circular will be sent on request. Postpaid, $3.00. RILEY--Handbook of Medical Entomology By WM. A. RILEY, Ph.D., Professor of Insect Morphology and Parasitology in Cornell University and O. A. JOHANNSEN, Ph.D., Professor of Biology in Cornell University. A concise account of poisonous, and disease-carrying insects and their allies, including descriptions and illustrations of the principal species, with keys for their determination, and method of control. Bound Library Buckram, medium 8vo. Nearly 375 pages. Price $2.00 net. _Send for Descriptive Circular_ The Comstock Publishing Company Cornell Heights, Ithaca, N. Y.