88 . THE TEACHING BOTANIST 



The lens fits in at one end and the needles, etc., at the 

 other ; and the case is intended either for keeping the 

 tools at the laboratory or for carrying them in the field. 

 A fair dissecting microscope may be made by placing 

 the lens open on the case, with the lenses, held in 

 position by one of the flaps, projecting over the side. 

 Next in importance are dissecting microscopes, which 

 are of the greatest value. There should be at least 

 one to a seat, preferably one to a student. There is 

 a large variety of these by different makers, and of 

 great range of excellence and cost. For a cheaper 

 kind, the Barnes Dissecting Microscope offered by 

 Bausch and Lomb to schools and colleges at $1.88 to 

 $2.82 is excellent, and, in my opinion, ample for ele- 

 mentary courses. 



The compound microscope is the chief tool of the 

 biologist and indispensable to the biological laboratory. 

 The ideal arrangement provides one for each student ; 

 after that, one to each seat where more than one 

 division uses a room ; after that, one to as few stu- 

 dents as possible. If there is one to each student, it 

 is easy to hold him responsible for its condition ; and 

 its life is so much longer that it pays in the end to 

 provide the greater number at the start. There are 

 all grades of compound microscopes and all prices. 

 The makers best known in this country are Zeiss, of 

 Jena (Germany), Leitz, of Wetzlar (Germany), Reichert, 

 of Vienna (Austria), and Bausch and Lomb, of Roches- 



