OXIDIZING POISONS 47 



the same time by the heat of a blowpipe flame without allowing 

 access of air. The specimen can now be kept for an indefinite 

 period before the germination test is made. 



63. Influence of Ammonia upon Protoplasm. Mount a leaf of 

 Philotria, or a hair showing movement, on a glass slip in the usual 

 manner. Note the rate of movement of the protoplasm by ob- 

 servations on the length of time necessary for a single granule to 

 traverse the length of the cell, or make a circuit of it, or move a 

 given distance as indicated by a micrometer scale. Now run in 

 at one edge of the cover-glass a 10 per-cent. solution of ammonium 

 hydrate, and note the effect upon the movement. After move- 

 ment ceases remove the ammonia by running in water at one edge 

 of the cover-glass and absorbing it with blotting paper at the other 

 edge. Note the restoration of the movement. Treat another 

 preparation to a concentrated solution of ammonia, and note the 

 effect upon the movement, and the consistency of the proto- 

 plasm. 



64. Effect of Ammonia Vapor upon Mimosa. Fill a watch 

 glass with ammonium hydrate and place it on a table beside a 

 vigorous, expanded specimen of Mimosa. Cover the whole with a 

 large bell-jar, being careful not to give the plant a mechanical 

 shock. Note the character of the movements which follow in a 

 few minutes. Remove the jar and note recovery of plants. Con- 

 tinued exposure will kill the plant as this compound of ammonia 

 is a poison. 



65. Nature and Action of Poisons. A large number of sub- 

 stances kill protoplasm when brought into contact with it, and 

 they may bring about the death of a complex organism by dis- 

 abling some special tissue or group of cells necessary to the con- 

 tinuance of some essential function. According to the manner in 

 which these substances act, they may be classed as oxidizing 

 poisons, substitution poisons, salt-forming poisons, and catalytic 

 poisons. 



66. Oxidizing Poisons. The normal process of the release of 

 energy in the prevailing types of the vegetal organism involves a 



