148 PREPARATION AND MOUNTING 



SECTIONS or BONE. With the aid of the microscope few 

 fragmentary remains have proved so useful to the geologists 

 and students of the fossil kingdom as these. From a single 

 specimen many of our naturalists can tell with certainty to 

 what class of animal it has once belonged. To arrive at 

 this point of knowledge much study is necessary, and sections 

 of various kinds should be cut in such a manner as will best 

 exhibit the peculiarities of formation. The methods of 

 accomplishing this will now be considered. It may, how- 

 ever, be first mentioned that the chippings of some bones 

 will be found useful now and then, as before stated with 

 flint, though this is by no means a satisfactory way of pro- 

 ceeding. Sometimes the bones may be procured naturally so 

 thin that they maybe examined without any cutting; and only 

 require mounting dry, or in fluid, as may be found the best. 



When commencing operations we must provide the same 

 apparatus as is needed in cutting sections of teeth, before 

 described. A fine saw, like those used for cutting brass, 

 &c., two or three flat files of different degrees of coarseness ; 

 two flat "sharpening" stones; and a leather strop with 

 putty-powder for polishing. As thin a section as possible 

 should first be cut from the part required by the aid of the 

 fine saw; and it is better when in this state to soak it for 

 some short time in camphine, ether, or some other spirit to 

 free it from all grease. With the aid of a file we may now 

 reduce it almost to the necessary degree of thinness, and 

 proceed as before recommended with teeth. The " sharpen- 

 ing " stone will remove all scratches and marks sufficiently 

 to allow it to be examined with the microscope to see if it is 

 ground thin enough ; and if it is to be mounted dry we must 

 polish it with putty-powder and water upon the strop to as 

 high a degree as possible, and having washed all remains of 

 polishing powder, &c., from the section we must place it 

 upon the slide and finish it as described in Chapter III. 

 But where these sections are required for mounting in 

 balsam a less amount of polish is necessary ; thus rendering 

 the whole process much more readily completed. 



