PLATE XII 
EXPLANATION OF PLATE XII 
P'ig. 37. Median longitudinal section through young sporogonium 
X 110. Coll. Aug. 15. Archesporial cells begin to differenti- 
ate into spore mother cells and those which will form elaters. 
f — foot, 
s — seta. 
V — calyptra. 
ar — withered neck of old archegonium. 
i — involucre. 
