ELEMENTS OF BOTANICAL MICROTECHNIQUE BY JOHN E. SASS, PREFACE Permanent slides for microscopic study are indispensable in the teaching of a basic course in botany and in some specialized advanced fields. In some advanced courses the students prefer many of the slides as a minor aspect of the course, but in elementary courses the slides usually are furnished. In the latter case the slides are either purchased from commercial sources or made in the departmental laboratory. Biological supply houses can furnish excellent slides of the subjects commonly used in elementary teaching, but the quality is likely to be variable, especially from concerns in which there is frequent turnover of the laboratory staff. Jobbing houses that purchase slides from constantly changing sources may also furnish disappointing slides at times. The more reputable concerns , however, try earnestly to meet the specifications of critical and reasonable purchasers. The relative merits of making slides and of purchasing them are in dispute and must be worked out in relation to local conditions Because of these uncertainties in the commercial supply and the need for specialized or unlisted items, the preparation of slides is an established service function in many biological departments. This work is often performed by a skilled professional technician with more or less supervision by the departmental staff. In other departments a member of the teaching staff, usually a morphologist, assumes this responsibility, with the aid of student assistants. Most research organizations maintain a technician for the preparation of research slides. There are many types of investigation in which it is possible for the technician to place the finished slides before the investigator, who then carries out the study and interpretation of the material. However, in many investigations some or all steps in the preparation require an intimate knowledge of the history, structure, and orientation of the material and the aims of the study...