BY R. VON LENDENFELD, PH.D. 31 



The success of making good sections depends firstly on the 

 quality and secondly on the position of the knife. No expense 

 should be spared to obtain the best razor possible for the purpose. 

 The knives, which are sold specially for the purpose, are always 

 bad and utterly useless. 



The razor can be fixed either at right angles to the direction in 

 which the knife is moved, or obliquely. The opinions as to which 

 is the best diSer. Caldwell and I use the knife vertical to the 

 direction of the motion. Further the plane of the knife itself can 

 be altered so that the cutting edge dips moi-e or less downward. 

 With an angle of about 12° to the plain in which the knife moves 

 the finest sections can be cut. The difiiculty of having the knife 

 so steep is that then the sections tend to curl up. 



This latter is a great evil and not altogether overcome by the 

 appliance of an outer carting of soft parafiine as recommended by 

 Caldwell. 



F. E. Schulze has in recognition of this difficulty of the curling 

 up of the sections constructed an apparatus which prevents it to a 

 great extent, so much so, that if Schulze's method is combined with 

 Caldwell's one can be pretty sure of obtaining good sections. 



A smooth round rod is fixed to the knife in such a manner, that 

 it lies parallel to, and just above the cutting edge so that any 

 section cut must pass through between the blade of the razor and 

 this rod, which can be attached by springs or screws to the back of 

 the knife. 



I would recommend therefoi-e that such an additional apparatus 

 be added to any of the Microtomes in trade. 



The outer coating of soft paraffin can be produced in a most 

 simple manner. 



When the paraffin is cold and hard, all the unnecessary parts 

 around the specimen are cut away with a knife so that only a 

 millimetre of paraffin is left on every side of it. The top is then 

 removed. The lower end, which is subsequently fixed in the 

 paraffin-holder of the Microtome should be cut down just to fit 

 into the holder. 



