ON EGGS OF MARINE ANIMALS 87 



6. Replace 80 per cent alcohol with two changes of 90 per 

 cent alcohol, each change for 30 minutes. 



7. Replace 90 per cent alcohol with 95 per cent alcohol — 

 two changes, 15 minutes each. 



8. Replace the 95 per cent alcohol with absolute alcohol — 

 two changes, 15 minutes each. 



9. Replace the absolute alcohol with xylene or toluene — 

 two changes, 10 minutes each. 



10. Imbed eggs. 



11. Section eggs. 



12. Mount sections. 



13. Dry sections. 



14. Place slides in each of following: 



(a) xylene or toluene — 5 minutes (to remove paraffin) 



(b) xylene or toluene — 5 minutes 



(c) absolute alcohol — 5 minutes 



(d) absolute alcohol — 5 minutes 



(e) 95 per cent alcohol — 5 minutes 



(f) 95 per cent alcohol — 5 minutes 



(g) 90 per cent alcohol — 10 minutes 

 (h) 80 per cent alcohol — 10 minutes 



(i) 70 per cent alcohol — 10 minutes 



(j) 50 per cent alcohol — 10 minutes 

 (k) 35 per cent alcohol — 10 minutes 



(1) water — 5 minutes 

 (m) water — 5 minutes 

 (n) 4 per cent ferric alum — 15 to 30 minutes 



15. Rinse the slides very carefully in 1000 cc. of water. 



16. Place slide in 0.25 per cent aqueous solution of haema- 

 toxylin for 3 to 5 hours or for 16 hours. 



17. Wash the slide in 1000 cc. of water. 



18. Place the slide in 2 per cent ferric alum; mount it under 

 low power of the microscope, illuminated by daylight, and 

 control the destaining. Arrest the destaining at intervals by 

 bringing the slide into water. When destaining has reached the 

 point desired, bring the slide into tap water. 



19. Wash the slide in gently running tap water for i hour. 



20. Run up the slide in alcohol as follows: 35, 50, 70, 80, 90, 

 95, 95, 100, 100 per cent, each for 5 minutes. 



