THE SCOURING-RUSHES 543 
Fic. 370.—Scouring-rush. A, male gametophyte or prothallus (432) show- 
ing antheridia (a, a). B-E, spermatozoids of various ages, much 
more highly magnified. (Hofmeister, Schacht.) 
Fic. 371.—Scouring-rush. Female gametophyte or prothallus (48) showing 
archegonia (a, a, a) and pseudo-roots (h). (Hofmeister.) 
in a cone-like aggregation of whorled sac-leaves. Each of 
these has a stalk ending in a shield-shaped expansion, six- 
sided from pressure. Behind each angle of the shield is a 
large sporangium dehiscing’ by a longitudinal slit (3, 4). 
The spores are peculiar in having four slender arms which 
close tightly about the spore when moist, and spread apart 
in drying, thus serving to eject the spores. They are there- 
fore called elaters (5, 6, 7). 
The massive, much-lobed gametophyte bearing gametangia 
above, and the comparatively large sessile sporangia of the scouring- 
rushes, indicate a closer kinship with the adder-tongues than with 
the true ferns, and suggest that the Equisetine may have evolved 
from Hepatic somewhat more moss-like perhaps than Anthoceros. 
They may be characterized as plants similar to ferns except in having 
