36 



THE OPHIOGLOSSALES 



exceedingly conspicuous. Bruchmann considers that the root and foot are both of 

 hypobasal origin, but he bases this on a comparison with the true ferns rather than 

 upon actual study of embryos, as he was unable to obtain embryos sufficiently young 

 to demonstrate this, and all trace of the original divisions disappears before any 

 sign of the stem and leaf is evident. It ma}' be well questioned whether, as in 

 Botrychium and O. pendulum, the foot does not take up the whole hypobasal region. 

 It is not impossible that the position of the basal wall may also vary in 0. vulgatum. 

 From a comparison with the embryo of 0. pendulum, I am inclined to assign more 

 of the embryo of the former to the foot region than is done by Bruchmann. 



In 0. vulgatum there is, finally, a differentiation of the stem apex from the 

 epibasal region, as in Botrychium and the true ferns, while in 0. moluccanum there 

 is no trace of a stem apex in the very young sporophyte, this developing later as a 

 bud upon the first root. 



From a study of Ophioglossum moluccanum and also of 0. pendulum it is 

 evident that the history of the young sporophyte in these species differs strikingly 

 from that of the other Pteridophytes. In both of these species the definitive sporo- 

 phyte always arises secondarily, as a bud upon the root, in the same way that 

 adventitious buds are commonly formed upon the roots of the adult sporophyte. 

 Bruchmann notes in 0. vulgatum the very precocious development of the primary 



Fig. 2o. — Ophioglossum pendulum. 



A. Transverse section of very young embryo. Xi8o. 



B. Longitudinal section of young embryo. Xl8o. 



C. Three transverse sections of an older embryo; l-l, basal wall; *■, primary root. Xl8o. 



D. .^ older embryo; r, primary root. 



root and the late appearance of the stem apex and first leaf; but in this species the 

 shoot apex, according to his statement, is derived directly from the epibasal half of 

 the embryo, as it is in most Pteridophytes. 



In Ophioglossum pendulum, where the development of the embryo seems to 

 offer no check to the further growth of the prothallium, the position of the arche- 

 gonium varies a good deal and it is impossible to tell from a section just what the 

 position was in the living state, as the branches of the gametophyte extend in all 

 directions and archegonia may be formed at any point upon their surface. To 

 judge from the youngest stages of the embryo that were met with (fig. 20). the basal 

 wall in this species is not necessarily transverse. In both of the cases figured it 

 was oblique, and more nearly longitudinal than transverse. It is likely, however, 

 that it is horizontal, or approximately so. In the four-celled embryo shown in 

 fig. 20, J, the quadrant walls were at right angles to each other, and tliis was also 

 the case in the five-celled embryo shown in fig. 20, B. Somewhat older embryos (C) 

 show that there is a pretty regular octant formation, and Bruchmann states that 

 this is also the case in 0. vulgatum. 



While in the typical ferns, and in Botrychium, all of the organs of the young 

 sporophyte can be traced to certain regions of the young embryo, in Ophioglossum 



