182 
PHARMACEUTICAL BOTANY 
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 5o°C. 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. 
2. Cyanophyce^; 
Plants which are sometimes termed blue-green alga. 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, stonewalls, etc. Examples: Oscillatoria, Glce- 
ocapsa, and Nostoc. 
Gloeocapsa. — This blue-green alga is commonly found on old, 
damp flower pots in greenhouses and on damp rocks and walls 
near springs, where it forms slimy masses. Under the micro- 
scope a mount of Gloeocapsa will be seen to consist of isolated pro- 
toplasts and groups of protoplasts, surrounded by concentric gela- 
tinous envelopes. Each protoplast consists of a protoplasmic mass 
which contains blue and green pigments. No definitely organized 
nucleus is apparent but chromatin in the form of granules is 
scattered through the protoplasm. The whole is surrounded by a 
