No. 483] STUDIES OF THE OPHIOGLOSSACE.E 



157 



sections are seen (Fig. 15, D), but it is evident that they are reall;^ 

 composed of several coalescent bundles. A slight indication of 

 this can be seen also in the adherent basal portion of the peduncle. 



CONCLUSIONS. 



From a study of the distribution of the bundles in the leaf it is 

 evident that the bundles which supply the spike are not second- 

 arily given off from the main bundles of the petiole, but are them- 

 selves the adaxial bundles which can be traced 

 from the base of the petiole into the spike. 

 This would indicate that the spike is not a 

 secondary development upon the leaf, but is a 

 primary portion of it. From a study of the 

 earlier stages of the young sporophyll as well 

 as from the conditions shown in 0. simplex 

 and certain forms of 0. pendulum and 0. 

 intermedium, there seems to be little question 

 that the spike is really a terminal structure, 

 and tlie writer is inclined to believe that in all 

 i as(>s the spike may be regarded as the apex of 

 iht' leaf structure and the lamina as lateral with 

 regard to it. If this view be not accepted, it 



of Mettenius, that the leaf is divided into two 

 equal branches. 



In connection with the question of the termi- 

 °^ nal position of the sporophyll, the position of 

 the leaf in the embrv'o may be cited. In 0. 

 moluccanum — and the same is true in 0. 

 •'^ prdunruh.vnn .U^scrihe.l fifty years ago by 

 Z Mettcnins,- thc vonn.o- sporopliyte (Fig. 16) 



strictly terminal organ. This (Mnl)ry() corroponds exactly to w hat 

 might be expected if the hypothesis advanced l)y the writer — tliat 

 Ophioglossum probably arose from some form resembling Antho- 



