TAXONOMY 227 



3. Reducing and Strengthening Bath: 



Gallic acid 5 



Tannin 3 



Fused sodium acetate 10 



Distilled water 350 



The flamed cover glass is first covered with the mordant for one- 

 half hour, or if in a thermostat at 5oC. for five to ten minutes. 

 The mordant is then carefully removed by thorough washing in 

 water, alcohol and water. The cover (film side up) is now put into 

 the silver bath (a few mils in a clean beaker or watch glass) for a 

 few seconds, during which time it is gently agitated. Without 

 rinsing it is next put into a few mils of the reducing solution and 

 gently agitated until the fluid begins to blacken. It is then washed 

 in water and examined. If not stained deeply enough the cover is 

 returned to the silver bath. It is finally dried and mounted in 

 balsam. All the dishes must be scrupulously clean. The fluids 

 must not be contaminated by the fingers nor by dipping iron or 

 steel instruments into them. 



Broca's Differential Stain. 



Loffler's Methylene Blue 80 mils 



Ziehl's Carbol Fuchsin * 10 mils 



Mix the solutions. 



This stain differentiates between dead and living bacteria. Dead 

 bacteria take on a red coloration and living bacteria a blue color. 



2. CYANOPHYCE.E 



Plants which are sometimes termed blue-green algce. They con- 

 tain chlorophyll, a green pigment, and phycocyanin, a blue pigment, 

 a combination giving a blue-green aspect to the plants of this group. 

 Found everywhere in fresh and salt water and also on damp logs, 

 rocks, bark of trees, stone walls, etc. Examples : Oscillatoria, Glce- 

 ocapsa, and Nostoc. 



Glceocapsa. This blue-green alga is commonly found on old, 

 damp flower pots in greenhouses and on damp rocks and walls 



