THE PARAFFIN METHOD 
123 
A TENTATIVE SCHEDULE FOR PARAFFIN SECTIONS 
It will be useful to give several tentative schedules for the use 
of beginners. It cannot be too strenuously insisted that these schedules 
are only tentative, their sole object being to give the beginner a start. 
The following is a tentative schedule for the ovary of a lily at any 
period before fertilization. The pieces should not be more than 
12 mm. in length. 
1. Chromo-acetic acid, 1 day. 
2. Wash in water, 1 day. 
3. 2\, 5, 10, 15, 20, 30, and 50 per cent alcohol, 3 hours each; 70, 85, 
and 95 per cent alcohol, 4 hours each; absolute alcohol, 6 to 10 hours, 
changing 2 or 3 times. 
4. Mixtures of absolute alcohol and xylol; 2\, 5, 10, 15, 25, 50, 75, and 
100 per cent xylol, 2 or 3 hours in each grade. Change the pure 
xylol once or twice. N 
5. Paraffin and xylol, 48 hours. 
6. Melted paraffin in the bath, 30 to 40 minutes. 
7. Imbed. 
8. Section; about 10 y is a good thickness. 
9. Fasten to the slide. 
10. Dissolve off the paraffin in xylol, 5 minutes. 
11. Xylol and absolute alcohol, equal parts, 2 minutes; 100, 95, 85, and 
70 per cent alcohol, 2 minutes each. 
12. Stain in safranin (alcoholic), 6 hours or over night. 
13. Rinse in 50 per cent alcohol, using a trace of HC1 if necessary; then 
in 70, 85, 95, and 100 per cent alcohol, 2 minutes each. 
14. Stain in gentian-violet dissolved in clove oil (or in clove oil with a 
little absolute alcohol), 10 minutes. 
15. Treat with pure clove oil until the gentian-violet stain is satisfactory. 
16. Rinse in xylol, 1 minute. 
17. Mount in balsam. 
18. Label. 
That the paraffin method is tedious and complicated is univer¬ 
sally recognized. Many substitutes have been tried, but without 
enough success to justify even a reference. 
