A RESUME OF THE USES OF FORMALIN. 73 



ner may be stained by either the Weigert or the Golgi method. 

 When the Golgi method of staining only is to be used, an equal 

 volume of a ten per cent, solution of potassium dichromate is 

 added to the formalin in place of the water. 



Dr. T. S. Cullen has devised two methods for using formalin 

 in connection with frozen sections. They are as follows : 



Method I. 



1. Keep sections made with the freezing microtome in a five 

 per cent, aqueous solution of formalin for three to five minutes. 



2. Keep them in fifty per cent, alcohol for one minute. 



3. Keep them in absolute alcohol for one minute. 



4. Wash them in water. 



5. Stain them in haematoxylin for two minutes. 



6. Decolourise them in acid alcohol (i'5 per cent. HCl). 



7. Wash them in water. 



8. Stain them with eosin for twenty seconds. 



9. Place them in ninety-five per cent, alcohol. 



10. Pass them through absolute alcohol, clear them in creosote, 

 or oil of cloves, and mount them in Canada balsam. 



The blood being lost in the frozen sections, the defect was 



overcome by fixing the tissue in formalin, and then making frozen 



sections as in 



Method II. 



1. A piece of tissue 1x2x5 centimetres is kept in a twenty 

 per cent, aqueous solution of formalin for two hours. 



2. Frozen sections are made. 



3. Keep them in fifty per cent, alcohol for three minutes. 



4. Keep them in absolute alcohol one minute. 



5 Wash them in water and stain them in haematoxylin for 

 two minutes. 



6. Decolourise them in acid alcohol (i'5 per cent. HCl). 



7. Wash them in water. 



8. Stain them in eosin for twenty seconds. 



9. Place them in ninety-five per cent, alcohol. 



10. Pass them through absolute alcohol, clear them in creosote 



or oil of cloves, and mount them in Canada balsam. 



Method I. is used for diagnosticating bits from tumours, and 



F insel 



