518 



LIFE- HISTORIES 



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

 earriers (archegoiiiophores). (Atkinson.) 



tophyte develops from a spore in much the same waj^ as happens 

 with the other liverworts described. P^ven more than in Riccia it is 

 like the thallus of ColeooliKte, notably in possessing but a single 

 chromatophorc in each cell, and in having no trace of pseudo-lea-\'es 

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

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

 which serves to liold 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 photosynthesize and so, unhke 

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

 ceros sporophyte sho.uld ever develop a root it would no longer 

 need to he even a partial parasite, as now, but co>ild lead an entirely 

 independent existence. Tlie elongating region connecting the cap- 

 sule and the foot is mori)liologically a shoot, and thus we have in 

 this little phint th(> beginnings of a differentiation into tliree mem- 

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



