Preface I'x 



useful standard methods. Intensive training can be given in the lew 

 processes wliich experience has shown to be the backbone of research 

 and which ha\e long served the routine needs in teaching. A course 

 of this type should be organized to give a systematic, graded series 

 of exercises, each exercise pointing to some definite objective and 

 yielding superior preparations of a given type. Student interest can 

 be maintained by working with plants that are of interest to the 

 student or the institution, and Avith plants that are characteristic 

 of the region. 



The trend in manuals of microtechnique has been in the direction 

 of encyclopedic works of wide scope. The extensive array of processes 

 in the research literature and reference manuals is bewildering to 

 beginners. Teachers have found it necessary to select and to assemble 

 suitable material in syllabus form. 



This manual has evolved over a period of years in connection 

 with the teaching of a college course in histological methods. The 

 course and the manual were designed to meet the needs of teachers 

 and prospective teachers of plant science, and the needs of beginners 

 in research in the basic and applied plant sciences. 



Since this is primarily a training manual rather than a reference 

 work, use is made of a graded series of assignments, beginning with 

 subjects in which orientation is easily visualized, few sectioning 

 difficulties are encountered, and a simple stain is used. Subsequent as- 

 signments require greater skill in the processing, sectioning, 

 and differential staining of cell and tissue components. A few care- 

 fully selected processing and staining methods are presented in detail. 

 Emphasis is placed on gaining an understanding of the aim of the 

 undertaking and the function of every operation, rather than on 

 memorizing and mechanically following a written outline of proce- 

 dure. After mastering the fundamentals, the worker can readily delve 

 into the literature of specialized fields by consulting the key references 

 in the brief bibliography. 



Compilation of the author's syllabus and records into book form 

 has been made possible by a grant from the Graduate College and 

 by assistance from the National Youth Administration. The drawings 

 were made by Miss Ruth McDonald. Grateful acknowledgment is 

 made for this aid. The author's colleagues and students have given 

 much valuable criticism, advice, and encouragement. 



John E. Sass 



Iowa State College, 

 August, 1951 



