APPENDIX 631 



through the foot, which thus becomes practically obUterated, and 

 breaking through the overlying prothallial tissue penetrates into the 

 earth. 



From the epibasal region there is developed the cotyledon, whose 

 axis is almost coincident with that of the primary root. Close to the 

 base of the cotyledon, which comprises the major part of the epibasal 

 half of the embryo, a second inconspicuous prominence arises, the 

 stem-apex. A single apical cell is probably present in all cases. 

 Tt is somewhat variable in form, usually four-sided in cross-section, but 

 sometimes triangular. The base is usually, but not always truncate. 



Both cotyledon and root elongate rapidly, and the young sporo- 

 phyte now closely resembles the corresponding stage of Ophioglossum 

 Mohiccamim, except for the presence of the stem-apex, which however, 

 is very inconspicuous. As in Ophioglossum the primary vascular 

 bundle extends as an uninterrupted strand from the cotyledon into 

 the root, and there is no stele developed in the stem region. In 

 Dancea the vascular bundle of the cotyledon is collateral as in Ophio- 

 glossum, but in the other genera it is concentric, although the phloem 

 is less developed on the inner side, and the bundle may approximate 

 the collateral type. 



As the second leaf develops it also shows an axial bundle which is 

 continued downward as the second leaf-trace, and unites with the 

 primary bundle to form the beginning of the vascular system of the 

 axis. No stelar tissue is developed in the stem region above the junc- 

 tion of the leaf- traces. 



P. 286. The cotyledon in Kaulfussia closely resembles that of 

 Ophioglossum, being oval in form and with reticulate venation. The 

 cotyledon in Dancea is similar in form to that of Kaulfussia, but the 

 venation is more or less completely dichotomous, with free veins. 

 In the other genera, the cotyledon is usually fan-shaped, with dichoto- 

 mous venation, but in Angiopteris and Macroglossum the venation 

 may be more or less pinnate in character. 



P. 287. The statement that the primary root of Marattia is 

 tetrarch is erroneous. It is usually diarch in all the genera, but may 

 be, exceptionally, triarch. 



P. 288. The development of the vascular system was critically 

 studied by the writer in Dancea and Kaulfussia, and to some extent 

 also in Marattia and Angiopteris (see Campbell {^3) ). All of the 

 genera agree as to the essential points of development. 



The vascular system of the young sporophyte begins as a single 

 axial strand which is continuous through the cotyledon and root. At 



