THE BRYOPHYTES. 179 



seta, which bears at its top a capsule. (See Fig. 103, F.) 

 A calyptra, or cap, with pointed apex, envelops the capsule 

 with long silky hairs. 



Find also sterile branches. These are recognized by 

 their pointed tops and the lack of the characteristics 

 already described for the male and the female branches. 

 Note the position and arrangements of the leaves and rhi- 

 zoids on each of the three kinds of branches. Draw each. 



2. Imbed in pith, celloidin, or 

 paraffin, pieces of the root end of the 

 stem and cut cross sections. Study 

 the structure under both low and 

 high power. Notice the imperfectly 

 differentiated epidermis, the cells 

 with thickened wall next within the 

 epidermis, and the somewhat distinct 



bundle of thin-walled cells, the axial Fm m _ Cross section 

 bundle, in the center. (See Fig. 104.) of the stem of the MOSS, 



T^ M j.i i i J.T, Bryum roseum, show- 



Describe the rhizoids as seen on the ^ simple differenti . 

 section. Draw the entire section. ation of the tissues at 



TT, nil,? i^ i J_T the center to form a 



Run Schultze's solution under the fib rovascuiar bundle. 



COVer glass. This Solution Stains The imperfect develop- 



._ , _. , ,. -~ ment of the bark and 



llgmfied Cellulose yellow. Do yOU the appearance of the 



find both normal cellulose and ligni- rhizoids are also shown. 



(After Goebel.) 



fied cellular tissue r 



Mount some of the rhizoids in water and examine under 

 low power. State how the cells are arranged. Do the 

 rhizoids branch? Draw a rhizoid. 



3. Examine a leaf under low power. Draw the entire 

 leaf. Do you find a midrib? Notice the teeth or spines 

 on the margin forms of plant hairs. Under the high 

 power draw one of the teeth and a few of the adjacent 

 cells. If dried material is used, the leaves should be 

 soaked in dilute caustic potash for twenty-four hours 

 previous to this observation to render them transparent. 



