286 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V, 



of the OpJiioglossacecE has long been known, and is mentioned by Russow 

 and HoUe in the works already cited. The latter refers to its presence 

 or absence, the varying number of protoxylem groups in the larger and 

 smaller roots of Botrychium matricaricefoliuni. In B. virginianuni this 

 explanation cannot be accepted, as, although the first formed roots vary 

 greatly in the number of archixyles, it is only in rare cases like that 

 figured in 68 that the fungus is present. 



VIII. 



The results of this investigation may be summarized as follows : — 



(i). The gametophyte of B. virginianuni is entirely subterranean,^ 

 without chlorophyll and probably symbiotic. It is from two to twenty 

 millimetres in length by one and a-half to fifteen millimetres in breadth^ 

 and oval in outline, whether viewed from above or from the side. 



(2). The whole surface of the plant is beset with rhizoids, which are 

 generally multicellular. The upper part of the gametophyte is occupied 

 in most prothallia, which have not yet produced embryos, by a median 

 ridge. The reproductive organs are found exclusively on the superior 

 surface, the antheridia being situated on the crest of the ridge, and the 

 archegonia on its flanks. 



(3). The gametophyte grows by a well-marked apical meristem which 

 is situated on the upper side, anteriorly, and apparently originates from a 

 single initial cell. 



(4). There is present in the lower part of the prothallus, an endophy- 

 tic fungus, possessing characteristics which will perhaps, on further 

 study, justify its recognition as a form intermediate between the genera 

 Pythiuni and Conipletoria. The symbiont is accompanied by a large 

 amount of oil, and probably advantageously affects the nutrition of the 

 prothallus. The fungus dies after one or more embryos have reached a 

 considerable size. 



(5). The antheridium originates from a single superficial cell and is 

 characterized by possessing a double outer wall. The antherozoids are 

 of the ordinary filicineous type and are rather large in size. 



(6). The arcJiegoniuni likewise takes its origin from a single super- 

 ficial cell. The neck consists of seven or eight tiers of cells. The 

 cervical canal-cell is binucleate, but is never represented by two cells. 

 A stratum of basal cells is present. 



(7). The first division of the fertilized &^^ is transverse, as in the other 

 eusporangiate Pteridophyta. The identity of the octant walls which are 



I 



