106 



LABORATORY AND FIELD EXERCISES 



or similar liverworts, using a hand lens. Are 

 the male and female organs aggregated or scat- 

 tered over the surface ? Are the plants monoecious 



FIG. 23. The female receptacle of Marchantia 



A, portion of a lengthwise section of a young receptacle 

 (semidiagrammatic), showing a row of archegonia hanging 

 down from the lower surface, the youngest heing nearest 

 the stalk (air chambers are present on the upper surface) ; 

 I, one of the ringerlike lobes back of the section (the diamond- 

 shaped areas indicate air chambers). B, a young sporo- 

 phyte within the parent archegonium (the region which is to 

 become the spore case is indicated by the cross lines, and 

 the small foot is attached to the base of the archegonium) ; 

 e, a special envelope developed around the archegonia of Mar- 

 chantia. From Bergen and Davis's " Principles of Botany " 



(with male and female organs in separate groups 

 on the same thallus) or dicecious (with male and 

 female organs on separate plants ? If the organs 

 are separate, how is fertilization to take place ? 

 (2) Sketch plants, showing the distribution of sex 

 organs. Label. 



