518 



LIFE-HISTORIES 



Fig. 341, I. — Umbrella-liverwort. Female plant (i), bearing archegonia- 

 carriers {archegoniophores) . (Atkinson.) 



tophyte develops from a spore in much the same way as happens 

 with the other Uverworts described. Even more than in Riccia it is 

 hke the thallus of Coleochsete, notably in jiossessing but a single 

 chromatophore in each cell, and in having no trace of pseudo-leaves 

 (Fig. 343). The gametangia are completely embedded in the thallus 

 (Fig. 344). The embryo (E) develops a somewhat expanded foot 

 which serves to hold the slender sporophyte in an upright position, 

 and functions also as an organ of absorption. As the sporophyte 

 continues to grow, however, it is plain that scarcely more than 

 inorganic materials are taken in; for very soon, above the foot ap- 

 pears an elongating zone of tissue containing much chlorophyll; 

 and this enables the sporophyte to photosynthcsizc and so, unlike 

 our other liverworts, to be almost self-supporting. If an Anthero- 

 ceros sporophyte should ever develop a root it would no longer 

 need to be even a partial jjarasite, as now, but could lead an entirely 

 independent existence. The elongating region connecting the cap- 

 sule and the foot is morphologically a shoot, and thus we have in 

 this little plant the beginnings of a differentiation into three mem- 

 bers — sporangium, foot, and shoot. At the center of the shoot and 



