CONNECTIVE AND ELASTIC TISSUES 453 



Prepare paraffin (or frozen) sections. Stain one to three minutes 

 in van Gieson's picric acid-acid fuchsin solution. Wash in 

 aq. dest. ; treat in 2 per cent. Nile blue sulphate solution in 

 aq. dest. for from two to twenty-four hours. Wash in changes 

 of aq. dest. till the latter is tinted pale blue. Stain again in 

 van Gieson one to five minutes. Wash in aq. dest. till wash- 

 water is pale yellow. Dehydrate rapidly with absolute alcohol 

 from drop bottle. Clear quickly in xylol (not more than a minute). 

 Differentiate in clove oil from five minutes to several hours (the 

 longer period is for frozen sections). Wash in xylol — -Canada 

 balsam. 



In successful preparations nuclear chromatin a saturated 

 transparent blue, mast cell granules nearly black, collagen red, 

 keratin and erythrocytes orange yellow (if bacteria are present 

 they stain blue). {Report of Imper. Cancer Research Fund, 1919.) 



