135 
A MerHop sy WuicH Cover Guassks May se Usep 
ON Gouct Surpes. 
By D. W. DENNIS: 
It has been well known for many years that Golgi slides of the brain, 
spinal cord, ete., will go bad if a cover glass is put on them. 
Several years ago serial sections of a mouse’s brain were prepared by 
this method in the Harlham laboratory by Mr. Levi Peacock. Three years 
ago I concluded to sacrifice one of these slides in order to get a medium 
power photograph of some Purkinje cells, so the balsam was warmed and 
the cover glasses put on. Last summer the slides were still in excellent 
condition. I accordingly had cover glasses put on ail the slides last winter 
and they are still all in good condition. Tlow long a time must elapse after 
a slide is made before it will bear a cover glass without damage we shall 
now work out. 
