THE EMBRYO 



143 



of the epibasal cells, so that this portion of the embryo is divided into four nearly 

 equal quadrants. There is some evidence that these are followed by horizontal 

 octant walls, so that the epibasal region is thus divided into octants in much the same 

 fashion as obtains in the whole embryo in other Marattiaceas and in the lepto- 

 sporangiate ferns. How far these divisions are constant can only be conjectured, 

 owing to the small number of young embryos which were available. The elongated 

 pear-shaped embryo in Dancea appears very different indeed, in these early stages, 

 from the broadly elliptical and much depressed embryos of corresponding stages 

 in the other Marattiaceae (fig. 114, C, D, E). 



Fig, 116. — D, jamakensis. 



Three sections of an older embryo. X200. Section B is a nearly median section; 

 A is the next section in the series; C shows the suspensor, sus, 



A further study of the embryos shows that all of the lower half of the epibasal 

 region, probably that derived from the four lower octants — i. e., the four octants 

 that were in contact with the suspensor — develops into the foot, while all of the 

 other organs of the embryo (leaf, stem, and root) arise from the four terminal octants. 



Quite early in the development of the embryo, there appears the same centrally 

 placed large cell which we have observed in the embryos of the other genera and 

 which, as we have seen, probably represents the primary stem initial. Brebner 

 concluded that a single initial was present in the stem of X). simplicifolia and this is 

 true of the three species examined hy me. The initial of the stem in Dancea becomes 



Fig. 117. — D. elUptica. 

 Three sections of a large embryo. X150. 5uj, suspensor; 5/, stem apex; co?, cotyledon; r, root initial. 



very easily seen in the older stages and is perhaps more clearly defined than it is in 

 any other of the Marattiaceae. Whether or not this cell can be traced back to one of 

 the original terminal octant cells is difficult to say, but it is quite possible. 



No single initial could be made out for the cotyledon, and it seems quite likely 

 that the position of the cotyledon is not always exactly the same, being determined 

 perhaps by the position of the embryo with reference to the light or to some other 

 factor. The cotyledon, as in Marattia and Angiopteris, first appears as a slight 

 prominence close to the nearly centrally placed stem apex, and there is soon visible 



