EVANS AND Hooker: PERISTOME IN CERATODON PURPUREUS 105 
Fic. 11-16. Cross and radial sections through the amphithecial tissues of 
older capsules, X300. 11 12, showing the peristomial layers in the region of 
the teeth, just before the deposition of the thickenings; 13, showing the same stage 
in the annular region; 14-16, showing early stages in the development of the thicken- 
ings 
the peristome but follows essentially the same method throughout 
the branches of the teeth. The portions of the strands deposited 
by the inner peristomial cells are broader than those deposited 
by the outer cells. They are therefore more conspicuous at first, 
but become less so later on. This is due to the fact that the 
inner portions of the strands develop to a slighter extent and in 
thickness only, while the outer portions give rise to the thick 
