EMBRYOLOGY 475 



degree of uncertainty. In B. virginianum it is traced by Jeffrey from the 

 epi basal hemisphere, and his drawings seem to bear this out. But in 

 '.ilgatum Bruchmann indicates a cell in the hypobasal region as the 

 probable initial cell. It seems not improbable that in the Ophioglossaceae, 

 as also in the genus Equisetum and among the Lycopodiales, the origin of 

 the root is not uniform in position, but may in this relatively large embryo 

 be at a point either above or below the primary segment-wall. 



A very striking feature in the young seedling is the early appearance of 

 the fertile spike. In O. viilgatum it may appear upon the third leaf, while it 

 may be seen even on the first leaf of the adventitious buds of this species. 

 In Botrychium Lunaria its minute representative may be found on the 

 rudimentary underground scales of the embryo. In these cases the body 

 actually seen does not seem to differ either in position or in origin from those 

 produced on the later leaves. Such facts will have their bearing on the 

 question of the morphological nature of the spike. Taken in relation to 

 the general theory of sterilisation they indicate that the plants are but little 

 removed from a condition where the very first leaves were fertile. On the 

 other hand, Jeffrey figures several fairly advanced plants of B. virginianum as 

 having no spikes ; but this species is one of advanced leaf-complexity. In 

 Helminthostachys also, in which the leaves are large and complex, Lang 

 has depicted young plants with expanded leaves, but without spikes. One 

 is disposed to conclude from these scanty facts that the simpler-leaved forms 

 of this family are more early fertile than those with more complex leaves, 

 an indication of their more primitive state : but further data are necessary 

 to substantiate the point. 



Lastly, there remains the case of B. obliquum, with its suspensor and its 

 complete inversion of the polarity of the embryo. It is difficult to see how 

 this is to be brought into relation to its biological surroundings. As the 

 details of this aberrant embryogeny are not yet to hand, it must for the 

 present be accepted as an objective fact, the chief interest of which lies in 

 the demonstration that such differences as presence or absence of a 

 suspensor, and consequent inversion of the initial polarity of the embryo, 

 are possible within near circles of affinity : this will have its important 

 bearing upon the comparison of Isoetes, where as in most Ophioglossaceae 

 there is no suspensor, with other Lycopodiales, in which a suspensor is 

 present and the embryogeny inverted as in B. obliquum. 



