1. 



Tlie Leaf and Sporoc arp of rvfcrcilia, 



Bot]i ^^enera of the Atirsiliaceae have "been the subject 

 of frequent study "bj'- "botanists since tlie earl;-- paH of t!as 

 centun/. But in spite of tliis tlie exact ori.^in, sequence and 

 developmeni" of th.e var'«ous or^^ans of the mature sporopli^di/e^ 

 and especially the morphiolo^^ical si.f^nif icerice of tlio sporo- 

 carp, liave never "been made out satisfactorily in either 

 genus. Th.is is undoubtedly due int/iemin to the dense coverinr; 

 of trichomes, over all th.e youir^ organs, wh.icli practically 

 prevents the successful study of these partn In toto as 

 transparent o"bjects. But it is due partly also to the com- 

 plexity of th.e apical "bud with, its confusion of numerous and 

 crov;ded, root, "branch, leaf and sporocarp rudiments, devel- 

 oping, except th.e last, in rapid succession from the segraents 

 of the apical cell of the stem. Still much has "been accomp- 

 lished even with tliis method and vath hajid sections, by 

 Bischoff , Mettenius, Hanstein and Russov;. T]ie introduction 

 of the paraffine metliod of sectionin-'; has largely overcome 

 the first difficulty, wliile making the second perliaps more 

 puzzlinr still. T}iis method in the liands of Menuier, Bfts-^en, 

 Cariipbell and others, lias added considerably to our knowle-'-^ 

 of tlie minuter details of development in these forms. 



The present work was undertaken at the surgestion of 



