WITH THE MICROSCOPE. 83 



cork, or lastly, it may be rubbed between two hones, a proceeding 

 which saves much time. 



It is to be ground down with the aid of a little water, and when 

 sufficiently thin it may be subjected to examination in the micro- 

 scope. It will, however, be found, that the beauty of the tissue is 

 completely obscured, owing to the number of scratches upon its 

 surface. These may be removed by rubbing the section first upon a 

 very smooth dry hone, and afterwards upon a piece of plate glass. 

 After the piece of bone has been properly polished, no lines will be 

 seen upon it, when it is examined in the microscope. 



153. Teeth. Sections of dry teeth cannot be advantageously 

 prepared in the manner just described, owing to the very brittle 

 nature of the enamel. The better way is to grind the tooth down at 

 a dentist's lathe until a section sufficiently thin be obtained. 



Sections of fresh bone and teeth may be prepared moist so as to 

 show many more important points in their structure and mode of 

 growth, according to the plan described in part V. After they 

 have been soaked for some time in glycerine and acetic acid, very 

 thin shavings even of enamel may be obtained with a strong sharp 

 knife. The calcareous matter may be dissolved out from specimens 

 by dilute hydrochloric acid, and sections of the decalcified matrix 

 easily cut with a sharp knife. 



154. Sections of shells of many of the lower animals, and the 

 hard shells and stones of fruit may be made in a similar manner, 

 but very hard textures such as fossil wood must be obtained of the 

 lapidary. See also " Of examining minerals and fossils," further on. 



155. Horn and Hair. Thin sections of horn and textures of 

 this description may be cut without difficulty with a sharp strong 

 knife, pi. XV, fig. 8 1. 



Hair. There are many ways of obtaining thin transverse 

 sections of hair. Thus a number of hairs may be united together 

 with a little gum, so as to form, when dry, a firm hard mass. 

 Thin sections of this can readily be made, with a sharp knife, 

 and the individual pieces may be separated from each other, by 

 the application of a drop of water. These may be mounted in 

 fluid, or dried and preserved in Canada balsam, 143. 



Or the hairs may be placed between two pieces of cardboard, 

 or between two flat pieces of cork, and when tightly pressed in a 

 vice, thin sections of the hair, including the cardboard and cork, 

 can be obtained with a sharp knife. For cutting thin transverse 

 sections of hair, my friend, Professor Weber, of Leipzig, recommends 

 a very simple expedient. He suggests that the beard should be 

 shorn very closely, and then after a few hours shorn again. In 



G 2 



