220 APPENDIX, 



CHAPTER XYI. (BACTERIA.) 



For the study of Bacteria it is very desirable to have a largo 

 species, and for this purpose there is none better than Bacillus 

 megaterium, which may be obtained from almost any bacteriologi- 

 cal laboratory and grown in the bouillon used by bacteriologists. 

 During 1895 and 1896 it may be obtained from Boston (see 

 above). This form is very large, and produces spores readily. 

 (See l)e Bary, " Lectures on Bacteria ;" Sternberg, "Bacteriol- 

 ogy;" Abbott, "Principles of Bacteriology;" etc.) The pro- 

 longed study of bacteria is not suited to beginners. Vinegar 

 bacteria may be seen in the mother- of -vinegar by pressing a bit 

 of it out under a cover slip and examining with a high power. 

 The jelly of mother-of- vinegar is a good example of zov<jl-<i. 

 The white scum which appears on aquaria and infusions i.- of 

 the same general character (zooglcea). 



CHAPTER XVII. (A HAY INFUSION.) 



To make a successful hay infusion care should be taken to 

 use water containing numerous and various organisms, and there- 

 fore distilled water, spring- waters, and well-waters, are in general 

 to be avoided. Tap- water should also be avoided if it is derived 

 from springs or wells. The best water for the purpose is that 

 drawn from ponds, rivers, lakes, or other surface sources. 

 Clean ditch or pool water is excellent. The choice of hay is less 

 important, but it is well to avoid old hay and hay that is \ -ry 

 woody. The infusion should be warmed, but not heated or 

 boiled. It may be kept in a beaker in diffuse daylight, e.g., in 

 a north window, the beaker being loosely covered. 



INSTRUMENTS AND UTENSILS.* 



The student should have access to the following articles : 

 A compound microscope with two eyepieces and low and 

 high power objectives (i.e., about 1 in. and in., or objectives 



* Most of the apparatus and reagents here mentioned may be obtained from 

 any first-class dealer in physical and microscopical apparatus, e.g., from The 



