

'i\ 



Materials and Equipment X 



This brief introductory chapter is intended for those who not only have 

 never made a microscope sHde but also have never even watched one being 

 made, so that they are unacquainted with the names of any of the pieces of 

 equipment used in its production. As these names will be used freely through- 

 out the other chapters in this book, it is well at the present time by reference 

 to illustration and descriptions to make sure that the beginning student knows 

 what the terms mean. 



Slides and Coverslips. The "microscope mount" consists essentially of some- 

 thing intended for examination under the microscope, which is held between 

 a "slide" and "coverslip." The slide is almost invariably a piece of thin glass 

 3 in. by 1 in., though on rare occasions big series of sections are mounted on 

 3- by iV^-in. or even 3- by 2-in. slides. It is a great mistake to use slides which 

 are too thin, for not only are they very easily broken but they also do not 

 work well with the condensers of most modern microscopes. A thickness of 

 approximately 1 mm. is the optimum, but slides as thick as 1 V4 mm. are per- 

 fectly satisfactory. It is essential that the surface of the slide be flat and that 

 the glass of which it is composed be as stable as possible for it will have to be 

 passed through a great number of reagents. These stable glass slides are usually 

 called "noncorrosive," and it is a great pity to use any other kind. 



Coverslips are circles, squares, or rectangles of thin glass; they are rarely, 

 particularly in the larger sizes, completely flat. They are made in four thick- 

 nesses known as No. 0, No. 1, No. 2, and No. 3, each of which has its own 

 special use. No. coverslips, which are about 0.09 mm. thick, are very dif- 

 ficult to handle and should be used only on preparations which are to be ex- 

 amined with an oil-immersion objective. They are rarely used today since most 

 people, even for immersion lenses, prefer a No. 1 coverslip, which averages 

 about 0.15 mm. in thickness. No. 1 coverslips are easier to handle and to clean 

 than are No. 0. No. 2 coverslips, which average about 0.20 mm. in thickness, 

 are generally used on wholemounts, which are not customarily examined with 

 the highest powers of the microscope. They are sufficiently thick to be easy 

 to clean without breakage and sufficiently thin to be used with anything except 

 an oil-immersion objective. No. 3 coverslips, averaging about 0.30 to 0.35 mm. 

 in thickness, are used only in making covers for dry wholemounts, which are 

 not described in this book. They should never be used for any other purpose. 



Circular coverslips are available in sizes from Vs to % in. in diameter, and 

 the size most commonly employed is a M in. (18 mm.). For class purposes a 



