100 PRINCIPLES OF PLANT-TBEATOLOGT. 



of the "spike" in Ophioglossicm may be regarded as 

 supporting this view. The " spike " is attempting to 

 revert to the original condition of two lateral " spikes." 



Chrysler, in an excellent paper, proves, once and for 

 all, both by conclusive anatomical evidence and by 

 teratological data, that the fertile spike in Opliioglos- 

 sum and BotrjjcJiinm represents a fusion-product of 

 two lateral segments of the sporophyll, one from either 

 side, and in Helminthostacliys the anatomy shows that 

 it represents a single lateral segment. In an abnormal 

 specimen of Botrychmm obliquum he observed two 

 fertile " spikes " partly fused together by their stalks 

 (fig. 110 &), and below them a larger fertile " spike" 

 representing the complete fusion of two. 



The fertile " spikes " of 0. palmatum are for all 

 practical purposes marginal ; some are actually so ; 

 but the strong distinction which Bower makes between 

 marginal and submarginal appendages is beside the 

 mark. Ovules, universally regarded as marginal 

 appendages of the carpel, ai'e very frequently, either 

 in their normal or virescent form, seated on the surface 

 of the carpel, some little distance from the margin, as 

 in the case of Banuncuhis Ficaria cited above. Mar- 

 ginal structures become very easily displaced on to the 

 surfaee of the leaf, a fact which does not prevent their 

 being regarded as morphologically marginal out- 

 growths. 



Regarded in this light the Ophioglossacese fall 

 naturally into line in the fern-series as regards the 

 conformation of their sporophylls. 



The wider homologies of these fertile segments of 

 the sporophyll in Ophioglossacese may here be alluded 

 to; they may be described as " enations " from tiie 

 upper surface of the leaf, and, as we have seen, they 

 represent the fusion by the outer margins across the 

 ventral surface of the sporophyll of two of its basal 

 lateral lobes ; the single lobe so formed is also for 

 a certain distance united by its ventral surface to 

 the median portion of the main leaf ; hence we have 



