ATRICHUM UNDULATUM. 89 



1. The stalk or seta. 



a. The length. 



b. Character of the surface. 



c. The slightly expanded end from which the cap- 



sule arises, apophysis. 



Take a specimen that has been boiled a minute or two in 

 potassic hydrate, and pull the seta from the leafy portion, 

 taking care that it does not break off, but comes away 

 smooth, and notice 



d. The pointed base. 



2. The pod carried by the seta, the capsule, with its calyp- 

 tra ; notice 



a. The manner in which the calyptra fits upon the 

 apex of the capsule. 



b. Shape of the calyptra. 



c. Pull away a calyptra and note its texture, and the 

 roughness of its apex. Draw. 



d. The shape of the capsule, and nature of the sur- 

 face. 



e. The hemispherical apex bearing a long beak, 

 together forming a removable lid, the operculum. 



/. The obliquity and slightly eccentric position of the 



beak. 



. Draw a capsule. 

 //. Pull off the operculum from a mature fruit, and 



notice the /-/;;/ of the capsule on which the edge 



of it rested. 



/. Rising from the rim, a large number of deli- 

 cate, incurved teeth, together forming the peri- 



stome. 

 / Count the teeth ; the number will be some multiple 



of four. 

 /-. The delicate epiphragm stretched between the 



apices of the teeth ; to be better displayed shortly. 



