A NEW BRAIN MICROTOME. 

 By Henry H. Goddard, A.M., Ph.D., 



Formerly Fellow in Clark University. 

 With Plates XIX and XX. 



There are now in use several forms of microtome for sec- 

 tioning a brain or other large organ. Some of these are merely 

 enlarged copies of the instruments in use for ordinary histolog- 

 ical work. Others are modified to some extent in order to bet- 

 ter adapt them to the more difficult work of producing so large 

 a section in perfect form. This difficulty is by no means small, 

 and in most of the instruments now to be had, is only partially 

 overcome. 



It is generally considered necessary to have the section cut 

 into liquid — water or alcohol — so that it can be floated out 

 smoothly. Two well known machines embody this principle. 

 One is the von Gudden. In this instrument the object to be 

 cut is embedded in a well of sufficient size to contain it, the 

 top of which is crowned with a rim of plate glass. By means of 

 a micrometer screw the object is raised in the well while the 

 glass rim serves as a guide for the knife which is moved " free 

 hand " over its surface. Outside of the glass rim is a good sized 

 pan which is filled with alcohol or water to such a depth as to 

 cover the knife. The section is thus cut under water and floats 

 off without injury. 



A more recent instrument is one invented by Bruce. ^ It 

 differs from the Von Gudden, chiefly in replacing the "free 

 hand " cutting by a machine cut. It consists of a heavy metal 

 tank 2 cm. deep, 20 cm. wide, 90 cm. long. A square middle 

 section is 6 cm. deeper than other portions of the tank. This 



' Described and illustrated in Journal of Nervous and Mental Disease, 

 Vol. 25, No. 12, Dec, 1898. 



