CHAPTER XIX. 



LABORATORY EQUIPMENT. 



236. Tables. In a school where the study of plants is to be 

 seriously pursued there should be a working room equipped with tables 

 of such size, and so arranged, as to give the students plenty of room 

 and light for their work. The ordinary school desks are not of suitable 

 construction and arrangement for laboratory work, and where a special 

 laboratory cannot be provided, it would be a good plan to fasten boards, 

 about eighteen inches wide, to the wall beneath the windows, by means 

 of strong brackets, to serve as working tables. Even where there is a 

 special workroom, such tables will be found very serviceable. The 

 main thing in any case is to have a flat working table, well lighted by 

 diffuse light, which will afford plenty of elbow room for each student. 



237. Microscopes. Much of the observation in an introductory 

 course in botany can be done with the naked eye, but for part of the 

 work a good simple lens is a neces- 

 sity. 1 It is economical to have cheap 



pine blocks made as stands for the 



lenses, after the manner of Fig. 196, 



rather than to purchase the stands 



of the dealers. Ordinary 2 by 4 inch 



pine scantling is dressed smooth, 



and cut into two lengths of 8 and 3 



inches respectively. It is better to 



bevel the ends of the short pieces. 



The short piece (b} is to be fastened 



to the long piece (#), as shown in 



Fig. i, by means of glue and a screw 



driven through from the lower face 



of the long piece. A brass rod (c) about ^ inch in diameter and 3^ 



inches long is driven into the short block, as seen in the figure, to a 



1 The doublet lenses manufactured by Bausch & Lomb, Rochester, N.Y., 

 are satisfactory for this purpose, those of |-inch focal length being the best 

 for general work. 



371 



FIG. 196. 



A simple dissecting microscope. 

 See text. 



