172 



definitive organs so arises, the root, and tbis becomes differen- 

 tiated at a very early period. One of the octants next the 

 archegonium (Fig. 1 1 7) becomes at once the apical cell of the 

 young root. This cell is very soon recognizable by its size and 

 shape, and quickly begins its regular segmentation. The pri- 

 mary cap-cell is soon cut off (Fig. 120) and fr^m this time on 

 the young root is very conspicuous. Figures 121 — 123 show 

 three transverse sections of an embryo about the same age as 

 that shown in Figure 120. The octant divisions are very 

 clearly marked here, and in section c, which is the uppermost 

 of the three, the large triangular apical cell of the primary 

 root is very evident. 



Two types of the older embryo were seen. One of these is 

 nearly globular in form (Figs. 124: — 125) the other elongated 

 (Figs. 126, 129). The former looks as if it originated from an 

 embryo in which the basal wall was transverse to the axis of 

 the archegonium; in the other it was probably more or less 

 vertical. It is probable that in the former instance the root 

 initial is one of the epibasal octants while the whole of the 

 hypobasal portion forms the large foot. In the second type it 

 is difficult to say which half should be considered epibasal, 

 and which hypobasal, but as in the other case one-half may 

 be considered to be root, the other half foot, the growth 

 of both being nearly in a plane at right angles to that of the 

 archegonium axis. Figure 125 is a nearly median section of an 

 embryo of the first type, and it is not unlike Jkffrey's Figure 

 48 of the embryo of Botrychimii virghiianum. The whole lower 

 portion, (hypobasal half), forms tlie very conspicuous foot, 

 while from the epibasal region the root is developing and al- 

 ready the rudiment of the second root (r^) is visible. Whether 

 the latter arises directly from the primary root or whether it 

 may arise independently from the second epibasal quadrant is 

 not quite certain. At this stage the central vascular bundle of 

 the primary root is clearly evident, but no tracheary tissue is 

 3^et visible. The cells of the epibasal part of the embryo are 

 evidently much more active, having abundant protoplasm and 



