GENERAL METHOD OF STAINING SPECIMENS 57 



Staining. All the various solutions should be in readiness, 

 best placed in the little dishes in the order in which they are to 

 be used, as a short delay in one of the steps may spoil the 

 specimen. 



A very useful instrument for transferring the delicate 

 sections from one solution to another is a little metal spatula, 

 the blade being flexible (Fig. 14). 



A still better plan, especially when the tissue is "crum- 

 bling," is to carry out the whole procedure on the glass slide. 



General Principles. The section is transferred from the 

 alcohol in which it has been kept into water, which removes 

 the excess of alcohol, from here into 



Dish I, containing the stain, where it remains five to fifteen 

 minutes. Then 



Dish II, containing 5 per cent, acetic acid (1:20), where it 



Fig. 14. Spatula for lifting sections. 



remains one-half to one minute. The acid removes the 

 excess of stain. 



Dish III, water, to rinse off the acid. The section can now 

 be placed under the microscope, covered with cover-glass to 

 see if the intensity of the stain is sufficient or too great. A 

 second section is then taken, avoiding the errors, if any; and 

 having reached this stage, proceeded with as follows: 



Dish I V, alcohol, two to three seconds, to remove the water 

 in the tissue. 



V. A few drops of oil of cloves, just long enough to clear the 

 specimen to make it transparent (so that an object placed 

 underneath will shine through). 



VI. Remove excess with filter-paper. 



VII. Mount in Canada balsam (xylol balsam). 

 Staining Blood Specimens. A drop of blood is spread on 



