142 



THE MARATTIALES 



THE EMBRYO OF DAN.EA. 



Brebner (Brebner 2) has described the older embryo of Dancea simpltcifolia, 

 but did not secure the earlier stages. The youngest specimens he figures closely 

 resemble in form a corresponding stage in the species studied by me, and the slightly 

 pointed basal region suggests the possibility of the presence of a short suspensor 

 in D. simpltcifolia like that which I have found in D. jamaicensts and D. elltpttca. 

 While my own collection of young embryos is not as complete as might be wished, 

 still enough stages were secured to show that at least D. jamaicensis and D. ellipUca 



Fig. 114. — Vanaa jamaicensis. 



A. ArchegoDlum containing a one-celled embryo. 



B. Outline of next section of same embryo. 



C. Three-celled embryo, showing suspensor, sus. 



D. Outline of next section of the same embryo. 



E. Three longitudinal sections of a four-celled embryo. 



F. An older embryo, which was shrunken. 



G. Diagram of F, showing probable arrangement of cells. 



differ remarkably from the other Marattiaceae that have been studied in the develop- 

 ment of a short suspensor, thus showing an interesting analogy with the embryo of 

 Botrychium ohliquum, described by Lyon (Lyon 1). Whether D. jenmani shows 

 the same peculiarity was not determined, on account of the failure to obtain the 

 young embryo of this species; but as in its later development it corresponds very 

 closely to the other species, it is highly probable that a suspensor is developed. 



cot 



Fig. 115 



A. A nearly median section of an older embryo of D, jamaicensis. The suspensor does not show in this section. 



B. Three sections of a young embryo of i).e//i/ii(ca. ius, suspensor. X200. 



Before the first division takes place in the embryo, the fertilized ovum enlarges 

 to several times its original size and becomes decidedly elongated. The first division 

 wall, as in the other Marattiaceae, is transverse, but of the two primary cells thus 

 formed the hypobasal one divides no further, or only once, and forms a short sus- 

 pensor which pushes up into the neck of the archegonium whose cells become more 

 or less completely disorganized (fig. 114, A). The next division wall is a nearly 

 median one in the epibasal cell, and this is soon followed by a second wall in each 



