MARCHANTIA 121 



D. The antheridia, or male sexual organs. These are borne on 

 stalked disks, with scalloped margins, and are called anther- 

 idial receptacles, or antheridiophores. 



1. Draw an antheridial receptacle, showing its relation to 

 the thallus and the number and form of the lobes of the 

 disk. Where is it situated with reference to the midrib 

 of the thallus ? 



2. Section the disk in pith. Note the antheridia situated 

 in cavities among the irregularly shaped air chambers. 

 Where are the yoimgest antheridia found ? Make a semi- 

 diagrammatic sketch showing these points. 



3. Study the structure of an antheridium. Observe the 

 short stalk and the cellular sperm case above. If the 

 antheridia are not sectioned, crush and note the contents 

 of older structures which will probably show the minute 

 developing sperms. Staining the material with iodine 

 may bring out some points more clearly. 



4. Microtome sections of the antheridial receptacles (Sec. 212) will give 

 abundant stages in the development of the antheridia and sperms, 

 and show clearly the structure and arrangement of the sperm mother 

 cells within the mature antheridium. 



E. The arohegonia, or female sexual organs. These are borne on 

 stalked structures, with long, finger-like processes arranged 

 like the ribs of an umbrella, and are called archegonial recep- 

 tacles, or archegoniophores. Are antheridial and archego- 

 nial receptacles ever found on the same plant ? Are cups 

 found on these plants ? 



1. Draw an archegonial receptacle, showing its relation to 

 the thallus and the number and arrangement of its finger- 

 like processes. Where is it situated with reference to the 

 midrib of the thallus ? 



2. Draw a view of the receptacle as seen from below, choos- 

 ing an old specimen. Older material will present sporo- 

 phytes, frequently called the fruits of the liverwort, in 



