8 INTRODUCTION. 



hair brush, a ring of the cement. Place the slide in a 

 horizontal position until the cement is dry. A second 

 and third application of the cement helps to insure 

 perfect firmness. 



This method of making permanent mounts will be 

 found useful with many of the lower forms of plants when 

 mounted entire, and with dissections and free-hand sec- 

 tions of the tissues of more complex plants. These 

 specimens may be mounted also in Canada balsam, a 

 method that gives greater permanency, but in some cases 

 the manipulation is more difficult. With microtome sec- 

 tions balsam will be found highly desirable as a mount- 

 ing substance. 



In studying the higher plants there will be found from 

 time to time specimens that illustrate especially well cer- 

 tain structures and adaptations to peculiarities of environ- 

 ment. It will be of advantage to preserve some of these 

 in the form of herbarium specimens. This may be done 

 by drying the plants between heavy blotters especially 

 prepared for the purpose, and afterwards mounting them 

 on heavy paper. 



By preserving entire plants and the best prepared 

 slides an individual or a laboratory will soon accumulate 

 a good supply of illustrative material. Both individuals 

 and laboratories, however, must guard against the danger 

 of collecting material that illustrates nothing. 



3. Drawings, notes, etc. In the systematic examina- 

 tion of an object two kinds of memoranda, descriptions 

 and drawings, should be made. The value of the for- 

 mer is usually conceded, but that of the latter is often 

 deemed too slight to repay the trouble. The importance 



