APPARATUS AND GLASSWARE. 719 



when more general directions usually answer. The author does 

 not believe it a good plan for the student to have written, 

 minute, directions for preparing the plants and experiments. 

 General directions and' specific help where there is difficulty, 

 until the student learns to become somewhat independent, seems 

 to be a better plan. 



APPARATUS AND GLASSWARE. 



The necessary apparatus should be carefully planned and be 

 provided for in advance. The microscopes are the most expen- 

 sive pieces of apparatus, and yet in recent years very good mi- 

 croscopes may be obtained at reasonable rates, and they are 

 necessary in any well-regulated laboratory, even in elementary 

 work. 



Microscopes. The number of compound microscopes will 

 depend on the number of students in the class, and also on the 

 number of sections into which the class can be conveniently 

 divided. In a class of 60 beginning students I have made two 

 sections, about 30 in each section ; and 2 students work with 

 one microscope. In this way 15 microscopes answer for the 

 class of 60 students. It is possible, though not so desirable, to 

 work a larger number of students at one microscope. Some can 

 be studying the gross characters of the plant, setting up appa- 

 ratus, making notes and illustrations, etc., while another is en- 

 gaged at the microscope with his observations. 



The writer does not wish to express a preference for any pat- 

 tern of microscope. It is desirable, however, to add a little to 

 the price of a microscope and obtain a convenient working 

 outfit. For example, a fairly good stand, two objectives (2/3 

 and 1/6), one or two oculars, a fine adjustment, and a coarse 

 adjustment by rack and pinion, and finally a revolver, or nose- 

 piece, for the two objectives, so that both can be kept on the 

 microscope in readiness for use without the trouble of removing 

 one and putting on another. Such a microscope, which I have 



