THE ANTHOCEROTE.E 



143 



in the other species, they cannot be accepted without more 

 satisfactory evidence. While in the main corresponding to the 

 embryo of Anthocej'os there are some interesting differences 

 which are closely associated with the structure of the older 

 sporogonium. The foot is smaller than in AntJioceros and 

 derived only from the low^est tier of cells. The columella is 

 decidedly smaller, and the archesporium, as well as the young 

 sporogonium wall, relatively much thicker. As in AntJioceros, the 

 archesporium does not extend to the foot, but is separated by 

 the zone of cells which there give rise to the meristem at the 



Fig. 70. — Notothylas orbicularis (Sull.)- A, B, Horizontal sections of the growing point witli young 

 archegonia ; C, cross-section of tlie apex of an archegonium, showing the arrangement of the 

 cover cells ; D, longitudinal section of a nearly ripe archegonium, X400. 



base of the capsule. The form of the embryo is different too. 

 It is pear-shaped and more elongated than in AntJioceros. 



As the embryo develops these differences become more 

 apparent and others arise. Fig. 71, C shows a stage where 

 the division of the archesporial cells has begun, and it is at 

 once apparent how much more conspicuous they are. It is 

 seen too that the outer cells of the upper part of the capsule 

 are also dividing actively, and that, compared with AntJioceros, 

 the apical part of the capsule retains its meristematic character 

 for a much longer period. Corresponding with this, the growth 

 at the base of the capsule is much less marked. The divisions 

 in the archesporium are much more active than in AntJioceros, 

 and also less regular. At first divisions occur in the upper 

 portion in all directions, so that above the columella there is 



