114 PHYSIOLOGICAL PROCESSES IN PLANTS 



into a threadlike plant, which finally develops into a leafy moss plant. 

 This produces sex organs at its tip, which correspond to the anthers and 

 pistils of an ordinary flower. An anther-like organ is called an antheridium 

 and produces male cells called antherozoids, corresponding to pollen. 

 These are able to swim (motile} in water, however. A pistil-like organ 

 (archegonium) contains a single, comparatively large female cell, called 

 an egg. 



Conclusions. 1 . By what means must the male cell reach the egg ? 



2. What method of generation is here illustrated ? Explain. 



3. When an asexual generation is followed by a sexual one, it is called 

 alternation of generations. Show how it is illustrated here. 



d. A Fern 



Observations. 1. Observe a common fern plant. Are there root, 

 stem, and leaf ? 



2. What is the color ? 



Conclusion. Could this plant be called a parasite ? A saprophyte ? 

 Explain. 



Observations. 1. Look on the under side of the leaves for small fruit 

 dots, or spore cases. How are they distributed ? 



Note. Plants producing asexual spores are called spore plants, or 

 sporophytes. Those producing sexual spores (gametes) are known as 

 gametophytes. 



2. Crush a spore case on a slide and examine it with low power. 

 (A good figure or chart may suffice.) What is the form of the spores ? 



Conclusion. What method of 

 reproduction is here shown? Ex- 

 plain. 



Observations. 1. Refer to a 

 good figure or chart, and find 

 what develops from the growth of 

 an asexual spore. Does it have 

 roots ? 



2. Find organs corresponding 

 to anthers and pistils on the small 

 plant (prothallus) which grows 

 from the spore. Just where are 



they located ? Note. The anther- 

 FIG. 33. A, Archegonium of fern; c, . ,. J 



canal ; e, egg. S, antheridium, which ldia and archegoma are here much 

 produces male fertilizing cells; C, an- as in the moss ' The male cells 

 therozoid or male fertilizing cell, are able to swim in ram or dew, 

 highly magnified. (After Strasburger.) so that they may reach the egg. 



