LIFE HISTORY OF A LIVERWORT 
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not all mature at the same time, as in the mosses and 
ferns, but new spores continue to form in the region of 
intercalary growth so long as growth continues. As the 
spores mature the tip of the sporophyte splits open, and 
the walls spread apart progressively, as spores lower down 
come to maturity. 
FIG. 165. Anthoceros. Photomicrograph of a longitudinal section of 
the sporogonium, and portion of the gametophytic thallus. Note the 
foot of the sporogonium, and the more darkly stained spores at the center, 
above. 
200. Distribution of Spores. In addition to spores, a 
portion of the tissue of the archesporium develops sterile 
cells or cell-rows, called elaters (Fig. 166). When these 
become dry, as the sporogonium splits open from the tip, 
