SPORE-PRODUCING MEMBERS 453 



is shown by comparison of Fig. 25* A and n. The similarity of these 

 simple fertile spikes to those of the smaller species of Ophioglossum, such 

 as O, Bergianuin, is plain enough : if we imagine the sporangia in this 

 plant to be somewhat more prominent, less bulky, and their position 

 slightly altered, so as obliquely to face the sterile frond, the result would 

 be such a type as is seen in the simplest forms of Botrychium. From 

 these simple forms to the more complex, even to those in which the 

 spike attains its largest development, is a progression which may be 

 traced by very gradual steps : the first of these steps is illustrated by 

 the Figs. 252 A, is, c: in the first figure (A) two lateral rows of simple 

 sporangia are seen: in (B) the place of 

 one sporangium is taken by two coherent 

 together, while in the third (c) there are 

 at the base of the spike, which is simple 

 above, two " branches," the one with two 

 sporangia and the lower one with three. 

 These specimens will illustrate the gradual 

 steps towards branching of the spike which 

 are to be found in the simplest types of 

 Botrychium, Sections also bring out some 

 interesting points: Fig. 252 E represents 

 in outline under a low power a transverse 

 section of a spike of Botrychium Lunar ia 

 traversing two of its lower branches longi- 

 tudinally, and following the series of their Botrychium , L. .*,,= three 



' t very simple spikes. A shows no branching, 



Sporangia: this Shows the acropetal SUCCCS- but only two rows of sporangia, of arrange- 

 ment like those of Ophioglossnm, but pro- 



SlOn of development Of the Sporangia, while jecting further. B and C show simple cases 



of branching enlarged. D, E show trans- 

 it Will be noted that the tWO lowest On the verse sections of spikes; D close to the 

 . . apex, E lower down ; the latter follows two 



right are Coherent tO form a SynanglUm a branches longitudinally, and traverses their 



_ sporangia. Note the synangium on the 



matter of common occurrence, and corre- right-hand branch, x about 20 . 

 spending to what is seen in Fig. 252 B. 



Such simple observations as the above, which might readily be extended 

 into further detail, will suffice to show that it is possible to illustrate, 

 from simple though otherwise normal specimens, how a transition may 

 have taken place from the' condition of the spike similar to that of a 

 small Ophioglossunt) through the simpler types of Botrychium to the more 

 complex branched spikes. 



But it is in the large B. daurifolium that a better opportunity has 

 been found of observing intermediate steps between the single normal 

 sporangium and a twin pair of them : the series Figs. 253 A-G illustrate this : 

 Figs. A, c show sections of young sporangia of normal type, with sharply 

 curved contour : others are of broader form, and show a considerable 

 mass of tissue on either side of the sporogenous group (Figs. D, E) ; 

 in these there may be seen cells laterally adjoining the latter, and 

 obviously of similar origin and position (x in Fig. D), which, though 



