COLORLESS PLANTS, OR FUNGI 1 



1. Mount a drop of stagnant water which contains decaying organic 

 material. Study the preparation carefully with the high power and note 

 the various types of Bacteria which are there present. The straight, rod- 

 like forms are bacilli; the corkscrew-like forms are spirilla; the 

 extremely small, spherical forms are cocci. Make a drawing of the field 

 under observation, showing all kinds of Bacteria found there. 



2. Examine, under the high power, permanent preparations of various 

 kinds of Bacteria and draw a few cells of each kind. For example: 

 (a) Bacillus subtilis. This is a very common example of decay bacteria. 

 Note the tiny rectangular cell bodies with definite cell walls, but with no 

 visible differentiation into cytoplasm and nucleus ; (b) Bacillus anthracis. 

 This is an important spore-forming pathogenic organism. Note that the 

 cells tend to adhere end-to-end to form a filament, or chain. This is due 

 to the action of an outer gelatinous capsule ; (c) Bacillus typhi. There 

 are usually three species associated which are very similar structurally. 

 They are all very tiny, thick rods which under high power (X 500) appear 

 almost spherical. 



3. Examine a flask of water in which some compressed Yeast and sugar 

 have been placed. Note the general characteristics of the fluid, including 

 the smell, color, and taste, and also the minute bubbles of gas which are 

 continually rising to the surface. Connect the flask with rubber tubing so 

 as to conduct the gas which is being generated through clear lime-water. 

 Note the precipitate which gradually forms in the liquid. This shows 

 that the gas is carbon dioxide, which unites with the calcium oxide in solu- 

 tion to form insoluble calcium carbonate. 



4. Mount a drop of the liquid from the flask, after stirring a little, and 

 examine with both the low and high power. Note the enormous numbers 

 of tiny oval cells, each one of which is a unicellular yeast plant. Inter- 

 spersed among the yeast cells are the much larger starch grains. Note 

 that many of the yeast cells show various-sized projections, or buds. 

 Some of the buds also may again bud before they are detached from the 

 parent cell, and thus temporary colonies are formed. Add a drop or two 

 of iodin solution at one side of the cover glass. Examine the preparation 

 at once under the high power, near where the iodin was placed. Note 

 the staining reaction of the yeast and the starch. The blue color with 

 iodin is a well-known test for starch. 



5. Make a large drawing to show the structure of a yeast cell, noting 

 cell wall, cytoplasm, generally with numerous tiny granules, and the 

 large vacuole. The nuclear material cannot be distinguished. 



iB. pp. 12-13. 

 253 



