Mosses, Ferns, and Horsetails. 287 



172. Examine with a lens the apices of some of the 

 leafy stems which are not bearing capsules. A diligent 

 search is likely to reveal two kinds of structures, very 

 small flask-shaped bodies, termed arcJiegonia, which bear 

 the eggs, and club-shaped bodies, termed antheridia, which 

 contain the sperms. Make drawings of all the members 

 thus far studied. 



173. Mount archegonia and antheridia in a drop of 

 water under a coverglass, and examine with medium and 

 high powers. Mount and examine, in the same manner, 

 some of the spores contained in the capsules. Draw as 

 seen with both low and high powers. 



174. Boil pieces of soft brick, and, after cooling, place 

 them in a dish of water so that they are but little sub- 

 merged. Scatter the spores over the brick, cover with a 

 bell jar, and set in strong diffuse light, but not in direct 

 sunlight. When delicate green filaments (protonemata, 

 singular protonemd) begin to appear over the brick, scrape 

 off some of them, mount in a drop of water under a cover- 

 glass, and examine with medium and high powers. Leave 

 the brick under the bell jar, replenish the water as needed, 

 and observe developments. 



175. Remove a leaf from a moss, mount in a drop of 

 water under a coverglass, and examine with a high power. 

 How many cells thick is the leaf? What is the form of 

 the chloroplasts ? Are stomata present ? Place a drop of 

 chloral hydrate-iodine on the slip in contact with the cover- 

 glass, and draw out the water with a piece of filter paper 

 placed against the opposite edge of the coverglass. As 

 the chloral hydrate-iodine replaces the water, watch the 

 effect upon the chloroplasts. Does starch appear in them ? 

 Do plants which have been kept in the dark give a differ- 

 ent result ? 



