POLYTRICHUM COMMUNE 77 



an end view of the sporangium with the operculum 

 removed. Make a drawing of the operculum, 

 also 30 mm. in diameter. 



1 8. With the razor carefully make a longitudinal section 

 of the capsule, just to one side of its central axis. 

 Observe the wall of the sporangium; a central 

 organ (columella) ; and, between the two, a mass 

 of spores. 



19. Describe the structural relation of the columella 

 to the epiphragm. What, in reality, is the latter? 



20. Describe the relative number, color and attach- 

 ment or non-attachment of the spores, so far as 

 may be ascertained without the aid of the micro- 

 scope. 



21. Make a drawing, ten times natural size, illustrating 

 everything observed under 18-20. 



22. From the above observations construct a diagram of 

 an imaginary cross-section of the sporangium near 

 the middle. Compare the diagram with an actual 

 cross-section. 



23. Carefully preserve the sporophyte in a covered 

 watch-glass or other convenient moist (not wet) 

 place until the next laboratory period, or proceed at 

 once with the following observations (D) : 



D. Microscopic Characters: 



THE SPOROPHYTE 



1. With a sharp scalpel remove a thin piece from the 

 base of the sporangium, cutting parallel to the sur- 

 face, and mount it in water with the outer surface 

 uppermost. 



2. Examine the mounted tissue under the low, then 

 under the high power, to see if stomata are present. 

 If they are, describe them and their distribution. 



