Cutting the Sections. 21 



distilled water and let them remain for 10 minutes or 

 longer, until the gum is dissolved out ; this will take 

 longer with some material, such as testicle, than others. 



With this microtome the most beautiful sections can 

 be cut perfectly even throughout, surpassing anything 

 that can be done with the hand. With care very large 

 sections may be cut quite as readily as smaller ones, 

 but to cut them well the razor must be very sharp, and 

 the material not too hard ; those hardened in chromic 

 acid mixture, No. 1 (page 11) seem to do the best. 

 Very little force is required in pushing the knife across 

 the material, and if it is sharp a very slight turn 

 of the screw each time will cut a section ; these ought 

 to be so thin as to be almost invisible, as the gum melts 

 on the razor. 



In cutting some material, such as retina, it is advis- 

 able to stain it en masse before freezing, otherwise the 

 sections cannot be seen when placed in water. 



