THE MICROSCOPE AND HISTOLOGY. 



CHAPTER I. 



THE MICROSCOPE AND ITS PARTS— CARE AND USE. 



APPARATUS AND MATERIAL FOR THIS CHAPTER. 



A simple microscope (§ 2, 4) ; A compound microscope with nose-piece (Fig. 17), 

 eye-shade (Fig. 16, 18 1 , achromatic (§ 12), apochromatic {\ 14), dry {\ 9), immersion 

 ($10), uuadjustable and adjustable objectives (§ 15, 16), Huygenian or negative 

 ($ 20, 22), positive (§ 21) and compensation oculars (§ 23), Abbe illuminator (54), 

 homogeneous immersion liquid (§ 10, 65-69), benzine and distilled water (\ 64, 

 69). Mounted letters or figures ($ 34) ; Ground-glass and Japanese filter or bib- 

 ulous paper ($ 34, 72) ; Mounted preparation of fly's wing (§ 50) ; Mounted prepa- 

 ration of Pleurasigma {\ 52, 53, 58) ; Stage or ocular micrometer with lines 

 filled with graphite {\ 52, 53, 59) ; Glass slides and cover glasses (| 52) ; 10 per ct. 

 solution of salicylic acid in 95 per ct. alcohol {\ 60) ; Preparation of stained mi- 

 crobes ($ 67) ; Vial of equal parts olive or cotton seed oil and benzine (§ 71). 



Of the above, the laboratory furnishes all except the tripod magnifier, the glass 

 slides and cover-glasses ; these must be obtained by the student. 



A MICROSCOPE. 



$ 1. A Microscope is an optical apparatus with which one may obtain a clear 

 image of a near object, the image being always larger than tbe object ; that is, it 

 enables the eye to see an object under a greatly increased visual angle, as if the 

 object were brought very close to the eye without affecting the distinctness of 

 vision. Whenever the microscope is used for observation, the eye of the observer 

 forms an integral part of the optical combination (PI. I, Fig. 4 and 5). 



\ 2. A Simple Microscope. — With tliis an enlarged, erect image of an object may 

 be seen. It always consists of one or more converging lenses or lens-systems (PI. 

 I, Fig. 1, 2 and 4), and the object must be placed within the principal focus (§ 4). 

 The simple microscope may be held in the hand or it may be mounted in someway 

 to facilitate its use (Fig. 8 a ). 



\ 3. A Compound Microscope. — This enables one to see an enlarged, inverted 

 image. It always consists of two optical parts, — an objective, to produce an en- 

 larged, inverted, real image of the object, and an ocular acting in general like a 

 simple microscope to magnify this real image (PI. I, Fig. 5). There is also usually 

 present a mirror, or both a mirror and some form of condenser or illuminator for 

 lighting the object. The stand of the microscope consists of certain mechanical 

 arrangements for holding the optical parts and for the more satisfactory use of 

 them (PI. II, Fig. 10). 



