278 TECHNICAL MICROSCOPY. 



be pushed into the liquid with the needle. In these matters much 

 depends upon habit and practice. We never use the brush for 

 this purpose. 



If the objects are suspended in a liquid, the pipette (Fig. 156) 

 is frequently used for collecting them and placing them on the 

 slide. If the upper end of the glass tube is closed with the 

 forefinger, the lower end, drawn to a fine point, may 

 be immersed in a liquid without the latter entering. If 

 then the finger is suddenly removed, a little of the liquid, 

 together with the minute bodies suspended in it, will rush 

 into the tube, and may be held there by reclosing the 

 upper end. The pipette is especially valuable for taking 

 up single specimens from various layers of liquid. 



The microtomes so much recommended in recent times 

 devices which are said to facilitate the production of thin 

 sections of hard tissues may be usefully employed in many 

 cases, especially where a greater extent and more uniform 

 thickness of the sections is required ; for instance, for the 

 cabinet of microscopic specimens. For scientific purposes, 

 however, we do not esteem them highly, since all we 

 require is to cut small portions of an object, or to find 

 suitable places for examining the sections. We agree in 

 general with Mold's opinion, that mechanical contrivances 

 which are to aid the artificially strengthened eye by the 

 artificially strengthened hand are of little scientific value, 

 and that simple devices are quite sufficient in skilful 

 hands, and are generally more serviceable than com- 

 ' plicated ones. We therefore omit a description of the 

 microtome the more readily as the manufacturers usually furnish 

 instructions with every instrument. 



Scissors are much used with animal preparations, but rarely 

 with vegetable ones; for the latter, ordinary small scissors are 

 quite sufficient. Similarly, the chisel, double-edged chisel, saw, 

 plane, &c., can hardly be reckoned among the instruments of the 

 microscopist, neither are the pocket-knife, hand- vice, pliers, punch, 

 &c., to be so regarded. The mode of employing these instruments 

 is in most cases self-evident : thus, the saw is used with hard 

 woods, bones, teeth, and similar bodies, for cutting them, or making 

 thin sections or plates, which are afterwards ground flat; the 

 plane is used with horny bodies for obtaining rather large sections; 



