WITH THE MICROSCOPE. 305 



3"8. Of the Preparation of Hard Tissues for Examination with 

 the Highest Powers, Bone, Teeth, &c. The methods generally em- 

 ployed, p. 82, for demonstrating the structure of bone, teeth, and 

 other hard tissues, only enable us to form a notion of the dead and 

 dried texture. The soft material is dried up before the section is 

 made. 



And yet this very soft material which is not represented in 

 the drawings published in many works, is that which makes the 

 difference between the dead bone or tooth, and that which still 

 remains an integral part of the living body. So far from this 

 soft matter being unimportant, it is the most important of all the 

 structures of the hard texture. It is by this alone that all osseous 

 and dental tissues are formed and nourished. From the arrangement 

 of this soft matter not having been generally recognised, the most 

 erroneous ideas have prevailed, and still prevail, upon the formation 

 and nutrition of these hard tissues. 



Even now it is generally believed that the dentinal tubes are real 

 tubular passages for conveying fluids to all parts of the dentine, and 

 are thus subservient to its " nutrition," and yet it is more than eight 

 years since Mr. Tomes proved most conclusively that these so-called 

 '' tubes " were occupied in the recent state by a moist but toler- 

 ably firm material (Phil. Trans., February, 1856). I have verified 

 Mr. Tomes' description, and am quite certain that the so-called den- 

 tinal tubes are not channels for the mere flowing up and down of 



nutrient fluid.* 



Suppose a tooth is to be prepared for minute microscopical in- 

 vestigation, we may proceed as follows. The same plan is applicable 

 to bone and shell. 



1. As soon as possible after extraction, the tooth may be broken 

 by a hammer into fragments, so as to expose clean surfaces of the 

 tissues. Pieces of dentine with portions of pulp still adhering to 

 them may then be selected and immersed in the carmine fluid, and 

 placed in a vessel lightly covered with paper, so as to exclude the 

 dust. The whole may be left in a warm room for from twenty-four 

 to forty-eight hours. 



2. The carmine solution may then be poured off. and a little plain 

 dilute glycerine added, p. 296. 



3. After the fragments of teeth have remained in this fluid for six 

 or eight hours, the excess, now coloured with the carmine, may 

 be poured oft", and replaced by a little strong glycerine and acetic 

 acid, p. 296. 



* On the structure of recent bone and teeth, see my lectures on ' ' The Struc- 

 ture and Grffzvth of the Tissues," Royal College of Physicians, 1860. 



X 



