122 LABORATORY AND FIELD EXERCISES 



gametophytes are abundant iu their natural habitat ? 

 Why not, since ferns produce abundant spores ? 



2. Habit. What group of plants already studied have game- 



tophytes most similar to those of ferns ? Is this group 

 closely related to ferns ? What is the most striking 

 difference between the ferns and the Hepaticae as 

 regards their gametophyte and sporophyte plants ? 



3. Structure. Wash the soil from the underside of mature 



gamete plants. Determine the structure of the plant 

 body and the nature of the absorbing organs. 



4. Sex organs. 



a. Study the position of the archegonia and antheridia on 



the ventral side of the gametophyte. Observe in 

 models and in the text the structure of these organs. 

 Are they essentially the same as those in the Bry- 

 ophyta ? How would fertilization be effected ? Is the 

 position of these sex organs favorable for insuring 

 fertilization ? Be able to explain. 



b. If sections are available, the student should study sec- 



tions cut through the gametophyte and the sex 

 organs for a more exact knowledge of the structure 

 of the archegonia and antheridia. 



c. Development of the gametophyte. Study germinating 



spores which show early stages in the formation of 

 the gametophyte. Draw and label stages observed. 



THE EMBRYO AND THE LIFE HISTORY 



1. Embryo. Study young sporophytes growing from game- 

 tophytes. What are the parts of the spore plant ? How 

 are they attached to the gamete plant ? What relation 

 does this young spore plant bear to the adult sporophyte ? 

 Consult the text figures on this point. 



