and Laboratory Methods. 2135 



1. Place the plant in a plate of water and draw the large thallus. Describe. 

 Note the holdfast, the flattened dichotomous frond, and the thicker central 

 region forming a sort of midrib. Note also the swollen tips of the branches 

 (receptacles), covered with numerous dot-like projections. 



2. Find the growing points of the thallus in branches which do not have 

 receptacles. Note the emarginate apices which have a slight groove lying in 

 the plane of the thallus. Draw under low power. The initial cells are at the 

 bottom of this groove. How are the branches formed ? 



'■]. Cut thin cross sections of a branch of the thallus with a razor, mount, 

 and examine under low power. Draw. Note the outer, denser, cortical layer, 

 and the looser, inner region, with elongated branched filaments and much 

 mucilage. 



4. Cut thin cross sections of a receptacle, mount, and examine under low 

 power. Note the conceptacles, cavities opening by means of ostioles on the 

 exterior. Sketch the entire section. 



5. Select a favorable conceptacle and draw, showing the ostiole, the wall of 

 the conceptacle, the sterile hairs, the large, dark-colored oogonia of oval form, 

 and the small yellowish antheridia situated on branched hairs. 



0. Under high power draw and describe a single antheridium showing cells 

 developing into spermatozoids. About how many sperms does an antheridium 

 produce ? 



7. Draw and describe an oogonium containing the eight ripe oospheres. 



8. Compare the egg and sperm cells. About how much larger in volume 

 is one than the other ? 



9. If fresh material can be obtained, study the spermatozoids and oospheres 

 after their escape from the sexual organs. Take a plant with mature receptacles 

 from sea water and expose it to the air for several hours. Mount some of the 

 exudation, which appears at the ostioles of the conceptacles. in sea water, and 

 examine under high power. Notice the large spherical oospheres and the 

 small motile spermatozoids. Study the process of fertilization, and describe. 

 Draw an oosphere surrounded by spermatozoids. The discharge of the egg 

 from the ovary into the water is a very unusual phenomenon in the plant 

 kingdom. Compare with Vaucheria and Volvox. 



Ohio State University. JoHN H. SCHAFFNER. 



Sectioning Stems and Leaves of Mosses. — Take a strip of heavy writing 

 paper— say ^-in. wide and l>^-in. long; on the middle of this spread a drop of 

 glycerine so as to cover a space about 3'2-in. long and ji-in. wide; put the part 

 to be sectioned on this space, the end to the right; place the paper on the stage 

 of a dissecting microscope and clamp it fast. With a pair of curved forceps in 

 the left hand to steady the part, and with a sharp scalpel in the right, commence 

 the cutting, watching the process through the lens. When a sufficient number 

 of sections have been made, scrape them with the dull blade of a penknife to a 

 dry part of the paper. If carefully done, the sections will adhere to the blade, 

 and may be easily transferred to a slide on which a drop of water has been 

 placed. Pick out the coarser sections, cover with a glass cover, and the re- 

 mainder are ready for the compound microscope. 



It is important not to have too much glycerine, and to spread it evenly ; a 

 knife-blade answers the purpose. The scalpel should have a keen edge ; a knife 

 will do if sharp enough. The parts to be sectioned should be soaked in warm 

 water for two hours at least, and longer if possible. — T/ie Bryologist. 



