POLYTRICHUM COMMUNE 87 



F, 1-6. The antheridia should be at least 25 mm. 

 long; the body of the sperms 10 mm. long. 



The archegonia 



8. With the female gametophyte make studies as 

 directed above (F, 1-4). 



9. In the archegonium distinguish the venter, neck, 

 and neck-canal-cells. Is the archegonium sessile 

 or stalked? 



-10. If prepared slides are available, identify the 

 oosphere, or egg, and, in mature stages, the neck- 

 canal. How many cells thick is the wall of the 

 archegonium? Is this uniform? What has become 

 of the neck-canal-cells? 



11. Make a drawing, at least 35 mm. long, showing all 

 features observed under F, 8-10. 



12. Describe the conditions, processes, and organs in- 

 volved in sexual reproduction in the moss. Explain 

 whether or not it is of advantage to the moss-plants 

 that they grow so close together. 



13. Into what does the fertilized egg develop? Where 

 does it develop? 



G. Nutrition and Growth: 1 



The gametophyte 



1. Is the gametophyte of the moss capable of elabor- 

 ating its own carbohydrate food? Explain. Is it 

 dependent upon the sporophyte at any period of its 

 existence? Explain. 



2. How does the possession of leaves affect the surface- 



1 This may be assigned for home work and serve as the basis of class 

 discussion, or of written work to be handed in. 



