and Laboratory Methods. 



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regions — foot, short stem, and tip. Remember that the mature sporophyte of 

 Marchantia has three parts. 



9. Draw a mature sporophyte of Polytrichum, showing the foot, the stalk 

 or seta, the hypophysis, and the capsule or sporangium. What important 

 advance has the sporophyte of Polytrichum and other mosses made over those 

 of Marchantia and Sphagnum ? Note that the sporophyte is a parasite during 

 its entire life. Does it manufacture any food for itself? 



10. Cut cross sections of the seta, mount, and draw under high power, show- 

 ing the epidermal layer, the band of sclerenchyma, the layer of thin-walled 

 parenchyma, and the central strand. The central strand of the sporophyte may 

 be compared with the vascular bundle system of higher plants. 



11. Ecological note. The hair-cap mosses are subject to great extremes of 



© 



@ — 



Fig. 9. — Diagram of life cycle of Polytrichum. 



moisture and dryness. Let a gametrophyte dry out and then place in water. 

 What occurs ? What adaptation has Polytrichum for checking the rapidity of 

 evaporation ? 



12. Make a diagram in the notes showing the life cycle of Polytrichum 

 (see Fig. 9). 



LI. O^/ier Mosses, (a) Hypnum radicale Beauv. {Amhiystcgium varium 

 (Hedw.) Lindb.) 



Order, Bryales. Family, Hypnaceae. 



This is a common moss on decaying logs, in moist, shady places, and on wet 

 ground. Preserve in 70 per cent, alcohol. 



Sporophyte. 



1. Take a nearly mature sporophyte, lay it on a slide and examine without 

 cover-glass under low power. Pick off the calyptra if still attached and the oper- 

 culum, being careful so as not to injure the delicate teeth of the peristome. 

 Draw the operculum and the calyptra. 



