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PART II. VEGETABLE HISTOLOGY. 



A good sharp razor or other suitable knife, for making thin, sections of 

 objects for microscopic study. 



A pair of sewing needles having their heads forced into wooden handles, to 

 serve for the dissection of tissues. 



A small earner s-hair brush for transferring sections to a slide, and generally 

 for the manipulation of small objects or structures of delicate texture. 



A glass tube of about one-fifth inch caliber, and a glass rod, each about six 

 inches long and having the ends rounded in a flame. They are serviceable in 

 transferring small quantities of test solutions, etc., from the containing bottles 

 to the object to be tested. 



A quantity of glass slides, 3 inches by 1 inch, having ground edges, and as 

 many square or circular cover-glasses of moderate thinness, and having a diame- 

 ter of about ^ of an inch. 



A rule, graduated on one edge in inches and sixteenths of an inch, and on 

 the other in decimeters, centimeters and millimeters. 



An eye-piece ?nicrometer. The form which we prefer as most convenient 

 consists of a cover-glass, not too thin, on which one-fifth of an inch is divided 



Fig. 461. — Eye-piece Micrometer. 



into ten equal divisions, and one of these spaces near the middle of the scale is 

 subdivided into ten equal parts, as shown in Fig. 461. The lines should be cut 

 rather deep and filled with black-lead ; the cover glass should then be mounted 

 in balsam, the ruled side downward, on a clear piece of somewhat thicker glass, 

 ground to such dimensions that it will fit easily inside the eye-piece and rest 

 on the diaphragm between the two lenses. Such an eye-piece micrometer may 

 also be made to answer all the ordinary purposes of a stage micrometer by 

 attaching it to an ordinary glass slide by means of a little water. It will be 

 held with sufficient firmness by the capillary attraction. 



A camera lucida, as an aid in drawing. A simple and inexpensive form, 

 though less convenient to use than some others, because it is necessary that the 

 microscope tube be in the horizontal position, is the neutral tint camera lucida, 

 which consists essentially of a piece of neutral tint glass placed immediately 

 back of the eye-lens at an angle of 45 with the axis of the microscope. But 

 the camera lucida which we prefer above all others, is the Abbe, illustrated in 

 Fig. 462 and manufactured by Carl Zeiss of Jena. The instrument is fastened 

 upon the eye-piece by means of the clamp-screw at the left. The drawing sur- 

 face is made visible by double reflection from the large plane mirror at the 

 right and from the silvered surface of a small prism placed in the visual point 



