Minnesota Plant Life. 



127 



cells are liberated in the water which may have accumulated as 

 dew or rain, or is, perhaps, the natural habitat of the plant. 

 Each spermatozoid is provided with a pair of swimming threads 

 by means of which it propels itself with great agility. Mean- 

 while upon the same plant, or upon neighboring plants of the 

 same species, there have been developed egg-producing organs. 

 These arise, mingled with glandular hairs upon the ends or 

 surfaces of branches and consist at first of solid masses of cells, 

 consisting of two 

 well-marked areas, a 

 spherical base and a 

 slender neck pro- 

 t r u d e d outwardly. 

 When the egg-pro- 

 ducing organ is ripe, 

 the cells at the end 

 of the neck separate 

 from each other and 

 a central row of cells 

 in the neck turns 

 into mucilage and 

 oozes out, leaving at 

 the bottom a large 

 egg-shaped cell now 

 inclosed in an organ 

 shaped like a bottle 

 with a long, slender, 

 hollow neck. The 

 opening from the 



exterior down to the egg is produced by the transformation into 

 mucilage of a row of cells as has been described. 



Reproduction of mosses and liverworts. All mosses and 

 liverworts produce sperms and eggs. Attracted in some man- 

 ner by chemical substances dissolved in the water near the eggs, 

 the spermatozoids find their way to the mouth of the egg-pro- 

 ducing organ. They crowd into its neck, swimming down the 

 canal which has been opened for them until they reach the egg 

 lying at the bottom of the flask. One sperm more active than 

 the others, or first upon the ground, buries itself in the sub- 



FIG. 42. Tip of a leafy moss plant, sectioned lengthwise and 

 magnified. The flask-shaped egg-organs, one with an egg 

 in place, are shown. These bodies are barely visible to 

 the naked eve. After Atkinson. 



