128 GENERAL BIOLOGY 



The student should study: i) in the fresh thallus, its 

 form and mode of branching, the location of its growing 

 points, its exposure to light. 2) The areas about the pores 

 of the upper surface (the details of the latter will easily be 

 made out in thin tangential sections cut freehand with a 

 razor from the upper surface). 



3) The scales and rhizoids of the lower surface and the 

 attachment to the soil. 



4) The details of structure of archegoniophore and anthe- 

 ridiophore. Study vertical sections of these, if such be at 

 hand. 



5) The details of structure in cross sections of the thallus 

 (possible in freehand sections from fresh tissues, but pre- 

 pared sections will be much better, if well prepared) . 



6) The excessively elongate cells of the axial bundle of 

 the stalk of the mature (easily withdrawn with forceps 

 from the stalks preserved in formalin, and should be 

 mounted outspread in a drop of water or formalin solution) . 

 Compare these in form with those of the outer wall of the 

 stalk. 



7) The mature sporophyte (easily dissected out with 

 needles under a lens) . Study also its development from the 

 egg, if slides are available for this. 



8) The form and structure of the spores and of the elaters. 



The record of the work done may consist of notes on and 

 drawings of the more important structures studied. 



9) The structure of the moss sporangium (ep.sily made out 

 in longitudinal sections: freehand sections will do for this, 

 if permanent slides are not available) identifying the parts 

 mentioned in the explanation to figure 76. 



PTERIDOPHYTES. FERNS, ETC. 



This is a group of plants of larger size than bryophytes 

 and of still greater diversity of appearance. It differs most 



