66 THE AMERICAN MONTHLY fMch 



terial, in which case cells with protoplasmic contents will 

 exhibit stained nuclei. In sections stained with Han- 

 stein's violet the cellulose will be found to be violet, and 

 the diffierent kinds of lignified tissue will exhibit diifer- 

 ent shades of red. Some sections may hare stained cell 

 contents ; proteids may be colored red with borax car- 

 mine ; starch may be colored pink with safranin or coral- 

 lin ; the callose of sieve tubes may be stained pink with 

 corallin or steel-blue with aniline blue. Sufficient has 

 been said to indicate that stains cannot be relied upon 

 solely to differentiate between the various elements in a 

 specimen ; they do, however, assist in differentiation be- 

 ings accomplished with greater clearness and certainty. 



Clearing. — The student should be careful to observe 

 whether the cell contents have'been removed by clearing, 

 as the difference between a cleared and non-cleared slide 

 is so great as to mislead a casual observer. 



Sketches. — How can the inherent characters of the 

 specimen best be apprehended ? By observing the vari- 

 ous tissues in a regular order, and transferring the ob- 

 servations to paper in the form of a sketch. The value 

 of the observations will be greatly increased if the sketch 

 is afterwards compared either with a published drawing 

 or description. The characters to be noted will, of course, 

 differ, according to the nature of the specimen ; but an 

 outline applicable to a few general cases may be useful. 



Stems, Roots, Rhizomes. — Beginning with the periph- 

 ery in plants in which secondary growth has not begun, 

 the epidermis and its appendages would be noted ; but in 

 drugs, if of the dicotyledonous type, the thick-ness of the 

 cork would be recorded. Then the primary cortex ; the 

 extention and comparative size of its cells ; the presence 

 and location of collenchymatous tissue; the presence and 

 location of slerenchyma,and whether in groups or a con- 

 tinuous ring, and if in groups, their frequency and form ; 

 jilso, if accompanied or otherwise with calcium oxalate 



