172 



Sections op Hard Tissues. 

 By T. C. White, F.R.M.S., 



{Read December 23rd, 1870.) 



One of the easiest preparations that young microscopists can try their 

 u 'prentice hand " on is the making of sections of the hard tissues, and 

 it is one attended with much interest in watching the gradual de- 

 velopment of structure where all was dark and opaque before. It is 

 not my intention this evening to dwell upon making sections of such 

 tissues as wood, horn, or hair, and such like structures, but to speak 

 more upon the making of sections of teeth for microscopic examina- 

 tion, as the mode generally adopted in this case is applicable to 

 such substances as shell of various kinds, and such hard tissues as 

 stones of the plum and peach, &c. It has been recommended by 

 writers on this subject that the section after having been cut by a 

 fine saw and reduced by a file, should be further rubbed down on a 

 hone, this plan has been attended with very good results in the 

 hands of some, but I wish to bring before the members this evening 

 the plan I have adopted for some time, and which I am rather 

 favourably inclined to. I proceed in the ordinary way to make a 

 thin section by means of the saw and file, reducing my section to 

 the thinness of an ordinary card, then, instead of using a hone, 

 which I find rather a slow process, I place my section between two 

 plates of ground glass, with plenty of water, and by rotating the 

 upper glass upon the second, I succeed in getting the finest and most 

 transparent sections. After using these plates some time the grain 

 of the glass gets worn away, and thus, if you keep your glasses, you 

 may get every degree of coarseness required, the oldest pieces put- 

 ting a final polishing to your section. If you desire to expedite the 

 first part of the grinding, a little finely powdered pumice stone 

 sprinkled between the plates will greatly assist the rapidity of the 

 action of the glass, especially in cutting such tough shells as that 

 of the crab and lobster. I have placed under the microscope this 

 evening the lower jaw of a weasel cut in this manner, and still 



