2572 Journal of Applied Microscopy 



3. Draw a branch of a rhizoid. How do these rhizoids differ from those 

 of Marchantia ? What relation is there between the rhizoids and protonema ? 



L. Polytrichuin commune L. Common Hair-cap Moss. 



Class, Musci, Order, Bryales. Family, Polytrichacese. 



The common hair-cap is a widely distributed moss which grows on the ground 

 in old fields and meadows, on hillsides and in woods. The plants are well pre- 

 served in a Mason fruit jar with 70 per cent, alcohol, and collections should be 

 made at various times from winter until early summer when the capsules are 

 mature. The plants are unisexual and the material for study should include 

 mature male and female plants, female plants with the embryo sporophyte devel- 

 oped just far enough to rupture the calyptra, and female plants with mature or 

 nearly mature sporophytes. 



Gametophyte. 



1. Draw the male and female plants (fronds) of the gametophyte generation, 

 showing the rhizoids, scales, and tip. If the plants are dry or taken from alcohol, 

 moisten in water. Note the rosette of scales at the tip of the male branch and 

 also the scales at the tip of the female branch. 



2. Take the tip of a mature male branch and dissect it with needles in a 

 watch-glass, mount the detached parts and examine under low power. Notice 

 the paraphyses and the white club-shaped antheridia. Do not mistake spatu- 

 late paraphyses for antheridia. Draw an antheridium under high power. Draw 

 a spermatozoid from a ripe antheridium. 



3. Study the living spermatozoids. These may be obtained if suitable male 

 branches are collected after several days of dry weather. Take one of the 

 branches and squeeze out the antheridia onto a slide. Mount in water and 

 observe the motile spermatozoids. 



4. If material is at hand, study and draw antheridia from a stained per- 

 manent mount. 



5. Dissect the tip of a female plant, mount the detached parts from the 

 center, and examine under low power. Draw an archegonium under high power, 

 showing lid-cells, venter, and stalk. In good specimens the oosphere may be 

 seen. 



6. If convenient, study prepared slides containing archegonia. Draw, show- 

 ing the stalk, venter, oosphere, neck, neck canal, and lid-cells. 



7. Cut cross sections of the scaly stem of a large specimen (using elder 

 pith and razor), mount in water and examine under high power. Draw, repre- 

 senting the epidermal layer, band of peripheral sclerenchyma, inner cortical layer 

 of thinner-walled cells, and central stand. 



Sporophyte. 



8. Select a female plant with a young sporophyte, pull off the calyptra and 

 then pull out the young sporophyte, being careful not to tear off its foot. Sketch 

 the calyptra under the dissecting microscope. What does the calyptra repre- 

 sent .'' Sketch the young sporophyte under dissecting microscope, showing three 



