260 E. T. NEWTON ON THE PUEPAKATION OF SOFT TISSUES. 



fixed was pushed up the inclined shelf. Supposing the razor to 

 have taken a slice off the wax and object when the holder was at 

 the lower end of the inclined shelf, then as the holder was pushed 

 up the incline, successive slices could be cut off. The top edge of 

 the upright plate was graduated so as to regulate the thickness of 

 the sections. 



The last machine referred to was the one which is described in 

 the January number of the '' American Naturalist" for the present 

 year, and is the invention of Prof. T. D. Biscoe. In this appa- 

 ratus the object to be cut is fixed by appropriate means to the 

 centre of a flat piece of glass. The razor is firmly screwed to the 

 under side of an open triangular frame, through each corner of 

 which a fine screw passes. The lower ends of the three screws rest 

 upon the glass plate, and consequently by turning the screws the 

 triangle and the razor may be gradually brought nearer to the brass 

 plate, and the operator is thus enabled to remove successive sections 

 of the object. The great advantage in this machine is that the 

 razor and its support can be moved in any direction, and if desired, 

 sections can be cut under the microscope. 



In concluding, Mr. Newton observed that a section-cutting 

 machine, in order to be trustworthy, should possess the following 

 qualifications, viz. : — 



1st. — It should be firm in all its parts, made of good solid material, 

 so that there may be no bending or shaking when in use. 



2nd. — It should possess a clamp, or some other arrangement, by 

 which it may be firmly fixed, so as to leave both the hands of the 

 operator free for manipulation. 



3rd. — The top plate upon which the knife rests should be perfectly 

 flat, otherwise the knife will " rock," and prevent that steadiness 

 which is necessary when thin sections are required. 



4th. — The regulating screw should work very truly and firmly, 

 for if this is not the case the sections will vary in thickness. 



5th. — The cutting instrument, whatever its form, must have a 

 thin and very keen edge. 



After the long discussion which followed the reading of this 

 paper, the author demonstrated the use of the section machine by 

 cutting a number of sections of spinal cord for distribution among 

 the members of the Club. 



