20 INTRODUCTION. 



ance as possible or without any. This requires patient 

 and thorough work. When done, however, and draw- 

 ings and notes have been fully recorded, it will be 

 advantageous to compare the work with the published 

 observations of others, and if any points have been 

 overlooked or misunderstood, to go over the ground 

 again. 



The following general treatises will be found suita- 

 ble for preliminary consultation, and when possible 

 should be constantly at hand on the laboratory shelves : 

 Gray's Structural Botany, Goodale's Physiological 

 Botany, Bessey's Botany for High Schools and Col- 

 leges, Sachs' Text Book, 2nd Eng. edition, Prantl and 

 Vines' Text Book of Botany, DeBary's Comparative 

 Anatomy of Phanerogams and Ferns, Strasburger's 

 Das botanische Practicum, Poulsen and Trelease's 

 Botanical Micro-Chemistry. 



If the student becomes interested in any particular 

 direction, the references given in the annotations, 

 together with those to be found in such of the works 

 just named as may be at hand, will usually give him a 

 fair start in tracing the literature of the subject, and 

 becoming acquainted with what has already been ascer- 

 tained in regard to it. This will indicate wherein 

 present information is defective, and enable him to 

 direct his labors toward a profitable increase of the 

 total sum of knowledge. 



The references have been preferably to works most 

 likely to be at the student's command, whenever these 

 have contained a sufficiently full treatment, this doubt- 

 less tending more to accomplish the desired object 

 of interesting the student and leading him on to 



