112 PHYSIOLOGICAL PROCESSES IN PLANTS 



from the neighboring cells of another filament, so that the contents of one 

 cell may pass over and mix with the contents of another. This is a 

 sexual method of reproduction. The part passing over is said to be the 

 supplying or male gamete, while the part to which it fuses is called the 

 receiving or female gamete. 



2. Can you find any cells emptied of their contents ? If so, what do 

 you find in the neighboring cell ? Note. The result 

 of conjugation or the union of the male and female 

 gametes is to form a new cell, called a spore (zygo- 

 spore, or yoke spore). The receiving gamete is said 

 to be fertilized. 



3. Can you find any such spores ? If so, do they 

 have thin or thick walls about them ? 



Note. These spores are also said to be "resting 

 spores " and correspond to seeds. The outer coat en- 

 ables them to resist freezing, drying, etc. Like seeds, 

 they sprout whenever the conditions are favorable. 



Conclusions. 1. Explain how these plants survive 

 the drying up of ponds in summer, or the cold of 

 winter. 



2. Write a paragraph on the sexual method of re- 

 ^w production in Spirogyra. 



=-| I 3. Write another paragraph on the advantages of 



FIG 31 Coniuga- tlie sexua ^ method of reproduction in Spirogyra. 

 tion of Spirogyra. 

 /, fusion in prog- (&) Asexual 



ress; zs, zygo- _^oe. The filaments of these plants break into 

 parts at certain times, and these parts form new 

 plants. This method of producing new plants is called asexual reproduc- 

 tion. 



b. A Fungus 



Materials. Ordinary mold on decaying fruits and vegetables, or on 

 bread. 



Observations. 1. What is the color of the mold ? 



2. Does it contain chlorophyll ? 



Conclusion. Can this plant manufacture its own food ? 



Note. Plants unable to manufacture their own food are much like 

 animals in that respect. If they live directly on living plants or animals 

 they are said to be parasites, while if they obtain their food from dead 

 bodies or organic wastes, as the molds do, then they are said to be 

 saprophytes. 



