114 



PLANT ANATOMY. 



The accompanying illastration repre- 

 sonts one of the simpler forms of the 

 Abbe cameras. The latest and most per- 

 fected instruments are to be recom- 



mondod. 

 In drawing, the microscope must be 



erect and the drawing table horizontal, 

 and the axis of the drawing should cor- 

 respond to the axis of microscope, else 

 distortion of the image will result. Spe- 

 cial drawing tables are in the market, 

 but are not necessities for the present 

 purposes, 



A polariscope attachment is of great 

 service in the hands of the pharmaceu- 

 tical microscopist, as it can abridge 

 many of his investigations. It is not, 



liowever, indispensable. 

 The Necessary Apparatus to be used 



in the investigation of vegetable tissues 

 is little. 



The following articles are essential; 

 Razor, preferably with a thin blade; 

 scalpel, forceps, caniol's hair brush, two 

 needles, glass slides, English pattern, 

 with ground edges arc to be preferred. 

 (These come in various sizes and thick- 

 nesses. For the beginner, a medium size 

 is preferable, %-inch and No. 3 in thick- 

 ness, it being less easily broken.). 

 Glycerine, blotting paper and lens paper 



will be found of service. To this list 

 of essentials many articles may be added, 

 as section lifters and microtomes, which 

 become necessary as soon as the student 



has advanced. 



General Directions for Work. 



The first requisite for good histolog- 

 ical work is cleanliness. All slides, cover 

 glasses and other apparatus in use 



should be kept free frou dust. 



Soft tissues cut differently from hard 

 tissues, hence they require different 

 handling. For the first a sharp razor 

 with a thin Made should be used; for 

 the second a sharp knife or scalpel, or 

 a thick-bladod razor is better. If great 

 care is taken both kinds of tissue can be 

 cut with the narrow bladed razor, but it 

 is wiser to be provided with both kinds 

 and to use them appropriately. This 

 same caution applies to the use of micro- 

 tome knives. 



Sections of tissues should be made with 

 an oblique motion of the cutting edge of 

 the razor, pulling it from heel to toe or 

 pushing from toe to heel. Many tissues 

 need moistening before cutting, especial- 

 ly the softer, pulpy kinds; for this pur- 

 pose a mixture of equal parts of alcohol 

 and water may be employed, or clean 

 water alone. The blade of the razor 

 may be kept moist by means of the alco- 

 hol and water mixture, although this is 

 not always essential. The object can 

 generally be held between the thumb 

 and forefinger, and the blade of the 

 razor resting upon the forefinger, it can 

 then be drawn or pushed obliquely 

 through the specimen. In general it is 

 not necessary to cut sections through 

 the entire width of the object, so that a 

 number of small sections may be made 

 by the oblique sawing motion of the 

 razor before removing them to the slide 

 for examination. Sections should be cut 

 as thin as possible. Practice alone will 

 enable the student to become expert in 

 this matter. The sections are then to 

 be removed by means of the camel's hair 

 brush to a drop of water left on the 

 center of the slide. Here they can be 

 arranged by means of the brush or 

 needles, and the cover glass placed in 

 position. The placing of the cover glass 

 may be done well or indifferently. After 

 cleansing it with lens paper, it 

 should be handled by the forceps only, 

 and placed upon the drop of fluid con- 

 taining the specimens, in as slanting a 

 manner as possible. This avoids includ- 

 ing air bubbles among the specimens. 



After the cover glass i^ in position the 

 surplus of water, if present, should be 

 romoTod by means of the camel's hair 

 brush or blotting paper; if there is not 

 enough water under the cover glass to 

 entirely surround the specimens, more 

 should be added by means of the brush 

 to the edge of the cover glass. 



The slide should then be placed upon 

 the stage, the object being as near the 

 center as can be approximated, when 

 the general directions for focussing 

 should be carried ont. 



