128 TYPE STUDIES 



4. Cultures of moss spores sown on earth (Sec. 206) will give a thick 

 growth of protonema which, when examined at the proper stage, 

 will show abundant buds and young leafy moss plants. 



C. Vegetative structure of the leafy moss plant. 



1. Mount a single leaf and examine under ni.p. Note the 

 line of elongated cells in the middle region, constituting 

 a simple midrib, and the simple cell structure of the ex- 

 panded portions on either side. Show these points in an 

 outline sketch. 



2. Examine a group of cells, if not previously studied 

 (Sec. 62), for the details of cell structure, chloroplasts, 

 nucleus, etc. 



D. The leafy moss plants bearing sexual organs. The sexual 

 organs may be found on separate moss stems, and such 

 mosses have consequently been called dicecious. However, 

 in some species the male and female stems have been found 

 to be joined at the base, so that they are really branches of 

 the same plant, which is consequently monoecious. Male and 

 female stems may also arise from the same protonema. 



1. The antheridial, or male, stems. These are generally 

 smaller than the female, and the leaves at the top of the 

 stem form an expanded rosette surrounding the cluster of 

 antheridia. Note the color of the cluster of antheridia 

 and their surrounding leaves. Draw an antheridial stem 

 to show these points. 



2. The archegonial, or female, stems. These are generally 

 larger than the antheridial stems, and the leaves at the 

 top are closely rolled around one another. Search for 

 such stems in a mat of mosses bearing mature antheridial 

 stems. Tease the leaves apart carefully at the tip under 

 a dissecting microscope, thus exposing the group of arche- 

 gonia. Make a semidiagrammatic sketch of the tip of the 

 plant, showing the relation of parts. 



E. The antheridia, or male sexual organs. Tease a cluster of 

 antheridia apart and mount. Note : 



