124 SPECIFIC EXAMPLES OF SLIDE-MAKING 



for, as the balsam oxidizes inward from the edge, it tends to remove the color 

 of the stain from the chromosomes, leaving them a rather unpleasant shade of 

 brown. If this happens to a valuable slide, however, the matter can be remedied 

 by the utilization of a green light which will make the chromosomes appear 

 black again. 



Summary 



1. Remove the testes from the scrotal sac of a young male rat and trim away 

 the epididymis. 



2. Slash the testes deeply with a razor, making cuts two or three millimeters 

 apart. Fix in at least 100 ml. of Allen's fluid from 1 to 7 days. 



3. Wash for about an hour in running water before removing small pieces to 

 70 per cent alcohol. Change alcohol daily until no further color comes away. 



4. Dehydrate, clear, embed in wax, and cut 5-m sections. Attach sections to 

 slide. Dewax dried slides and grade down to water through usual reagents. 



5. Mordant overnight in 2.5 per cent iron alum. 



6. Rinse briefly and stain overnight in 0.5 per cent hematoxylin. 



7. Rinse briefly and place in 2.5 per cent iron alum until chromosomes are 

 clearly differentiated. 



8. Wash in alkaline tap water until sections are blue. Dehydrate, clear, and 

 mount in the usual manner. 



