28 MICROSCOPY. 



(7) Label and lay aside in a horizontal position until balsam 

 hardens. 



Note. The above method may be used for all simple staining. 

 Special methods, however, are often used, and they will be given 

 as required. 



Laboratory Exercise No. 3. Centering and labeling. Upon the under 

 side of your box-cover make an outline of a slide. The pencil should 

 have a needle point. Connect opposite angles and place over the inter- 

 section of the lines a cover-glass. Be sure that the center of the cover- 

 glass coincides with the center of the diagram. Now, carefully make 

 an outline of the cover-glass. This outline may be used for centering 

 both the sections and the cover-glass. Make a drawing of this outline 

 on page 29, also a drawing of a slide with labels and cover-glass in situ. 

 Fill in the forms of labels in second diagram, using the following data: 

 A transverse section of the muscle of a normal cat was stained with 

 lithium carmine and mounted in balsam on October 1, 1891, by John 

 Smith. 



Drawings. For this work the student should provide himself with a 

 No. 5 or a No. 6 H Faber pencil, a small rule or triangle and a sheet of 

 thin blotting paper. The pencil should be kept sharpened to a needle 

 point. The majority of students will say: I cannot draw. An honest 

 and faithful effort will often produce gratifying results. Let every 

 line mean something. Be scrupulously neat in all your work. Remem- 

 ber that this work will furnish a better exhibit of character and abil- 

 ity than any other task of the laboratory. 



Abbreviations. The following abbreviations are employed in this 

 text: 



Transverse section T. S. 

 Longitudinal section L. S. 

 Vertical section V. S. 

 Low power L. P. 

 High power H. P. 

 Cubic centimeter c. c. 

 Micro-millimeter /z. 

 Millimeter mm. 

 Gram g. 



