GoDDARD, A New Brain Microtome. 2 1 1 



This gives sufficient room to manipulate the largest section of a 

 human brain, and a very small quantity of alcohol — a pint at 

 most — is sufficient for all requirements. 



The carriage for the brain, comprises two parts : an irmer 

 part to which the brain is fastened, and which slides up and 

 down within an outer part. The outer part slides horizontally 

 along a track from one end of the machine to the other. The 

 inner part is box-like, 7 x 6 x 6)^ inches, open on two sides. 

 It is very accurately adjusted to the outer case, within which it 

 is moved up and down by a micrometer screw. The head of 

 the screw is graduated so that a single click gives a section of 

 12.5 micra. The outer case is 11. 5 x 7-5 x 7 inches. It slides 

 between the two rails which form the track, and it extends 

 about half its length below them, thus securing great stability 

 and smoothness of movement. It is moved along the track by 

 means of a rack and pinion similar to that used on lathes. 



The dimensions of this carriage and the excursion of the 

 inner part are such that the largest human brain may be mounted 

 in any position, and sectioned completely from one end to the 

 other without waste or loss of material. Small sections are cut 

 equally well. 



In constructing the machine, the blade was first put in po- 

 sition since it must be exactly level in order to hold the alcohol. 

 The "cut" must be oblique, therefore the blade was placed 

 obliquely from the back left hand corner to the front right hand 

 corner of the supporting frame. In order to give the brain a 

 movement parallel to this obliquely placed cutting edge, the track 

 slopes downward from left to right; and in order for the brain to 

 pass under the knife and clear the bevel, the track slopes down- 

 ward from front to back. The amount of these two inclinations 

 can be judged from the pictures. 



In operating the machine, the brain is first embedded in 

 celloidin and mounted as nearly as possible in the plane in 

 which it is desired to section it, on a slab of suitable material — 

 vulcanized wood fiber is used at present, but this is liable to 

 warp if specimen is kept long in 80 % alcohol. This slab is 

 then fastened to the top of the inner part of the carriage by 



