232 
STRUCTURE AND LIFE HISTORIES 
212. Sexual Reproduction. The reproductive organs 
of Ascophyllum (Fig. 174) are borne in chambers 
(conceptades) beneath the surface of the enlargements at 
the tips of the short branches. Since the branches bear 
FIG. 174. Ascophyllum nodosum. A, Cross-section through a female 
receptacle; B, spermagonia; C, ripe oogonium; D, eggs, freed from the 
oogonium, but still enclosed by the separated inner layer of the oogonial 
wall. (Redrawn from Thuret and Bornet.) 
the gametes they are sometimes referred to as gameto- 
phores. These chambers open to the exterior by short, 
narrow canals, the openings of which may be easily seen 
on the surface of the swollen tips. The inner surface of 
