E. T. NEWTON ON THE PREPARATION OF SOFT TISSUES. 257 



after the removal of the sections from the staining fluid, too much 

 of the colour is lost ; when this is the case, a proportion of spirit 

 should be added to the water used for washing. 



The method usually adopted for mounting histological prepara- 

 tions in Canada balsam was described. 



When describing the various " section -cutting machines " which 

 had been kindly lent for the evening by several gentlemen of the 

 Club, Mr. Newton observed that although some competent histo- 

 logists had gone so far as to say that section-cutting machines were 

 only used to make up for want of skill in the operator, he was of 

 opinion that a properly-constructed machine would be found to be 

 a very great advantage by most persons engaged in histological 

 work ; and, while admitting that very much might be done by 

 hand with an ordinary razor, he felt sure that in many cases much 

 more satisfactory work could be accomplished with the help of a 

 machine. 



Most persons who have tried the cutting of microscopic sections 

 of a piece of tissue imbedded in wax, will have found that it is no 

 easy matter to obtain a section of uniform thickness, and at the 

 same time sufficiently thin for examination with the higher powers 

 of the microscope. 



The object of a section machine is to hold firmly the substance 

 which is to be cut, and likewise to assist in guiding the knife so 

 that greater precision may be obtained. Cutting machines are of 

 two distinct kinds. 1st, those in which the knife has to move upon 

 a flat plate, and 2nd, those in which the knife is so fixed that its 

 cutting edge does not come in contact with anything but the sub- 

 stance which is to be cut. 



1st. — Machines in which the Cutting Instrument moves 

 UPON A Flat Plate. 



The first machine mentioned consisted of a brass tube fixed into 

 a hole in the centre of a flat brass plate, a solid plug being fitted 

 into the tube from below. The object from which sections are to 

 be cut is imbedded in wax, or tightly fitted into the tube in some 

 other suitable manner ; by giving the plug a twisting motion, it is 

 thrust into the tube, and the object made to project above the flat 

 plate ; a razor with a straight edge is laid upon the flat plate, and 

 the portion of the wax with the imbedded object which projects 

 above the plate is cut off. This simple apparatus was described so 



R 2 



