GENERAL MORPHOLOGY 437 



and fourteen fertile spikes. Of 70 specimens examined in Kew and the 

 British Museum, ranging from those with a single sterile lobe to eleven, 

 and from one fertile spike to seventeen, the totals came out as follows : 



Specimens observed, 70 



Sterile lobes, - 328 



Fertile spikes, 373 



When these figures are taken together with observation of special cases 

 as illustrated in the drawings, they demonstrate a substantial parallelism 

 between the number of sterile lobes and of fertile spikes, though this 

 parallelism cannot be pursued into exact numerical detail. It is plain, 

 also, as illustrated by the above figures, that the leaves with most lobes 

 are those which are broadest and have the largest assimilating surface ; 

 thus, speaking generally, the number of fertile spikes increases with the 

 increasing leaf-area. 



It has already been pointed out that spikes in a truly marginal position are 

 rare; they do, however, occur, and Fig. 238 H shows one, together with its 

 vascular connection with the marginal bundle of the sterile frond. The 

 individual spikes correspond in form and general structure to the single 

 spike of O. vulgatum. But many of them show various stages of branching. 

 The following drawings (Fig. 239) illustrate such steps as may be seen 

 in Ophioglossum palmatuin : In Fig. 239 A are two spikes, each with an 

 imperfect lateral branch, but in both the series of sporangia is continuous 

 over the lateral protuberance. At the apex of each of the spikes of 

 Fig. 239 D is an indication of branching of the same nature. The branching 

 may be more elaborate, as in Fig. 239 B, where there are three borne upon 

 one stalk, the series of sporangia along the margins of them all being 

 interrupted, while it may also be noted that the vascular bundles are 

 united below in the common stalk. But in other cases the series of 

 sporangia may be interrupted (Fig. 239 c), so that the two branches now 

 appear as two distinct spikes seated upon a common stalk, though the 

 central vascular bundles unite below into a common bundle before their 

 insertion on the vascular system of the sterile frond. Figs. 239 D and E are 

 substantially similar, but show a more complete separation of the vascular 

 supply for the two spikes; while Fig. 239 F shows two spikes in which the 

 stalks are completely separate to the base, though the two are inserted 

 close to one another, and in the same relative positions as the branches 

 in Figs. 239 c, D, and E. 



The above series thus illustrate successive stages leading up to complete 

 branching of the fertile frond. It has been suggested by Bitter ' that the 

 simpler examples are really young plants of O. palmatuin, and it seems 

 not improbable that this may actually be the case, and the progression 

 be illustrated in the advancing life of the individual. However that may 

 be, it is by comparison of O. pendulum and of abnormal cases of 



1 Engler and Prantl, i., iv., p. 45* . 



