THE PROTHALLIA OF ANEIMIA AND LYGODIUM 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 136 
EpitH Minot Twiss 
(WITH PLATES X AND XI) 
A survey of the literature on the prothallia of the Filicineae brings 
out plainly two points: (1) for a number of years those who have 
studied this side of the life history of ferns have urged that one must 
not consider the heart-shaped prothallium, whose development was 
first worked out, the norm from which all variations are comparatively 
rare exceptions; (2) many investigators have expressed the conviction 
that gametophytic characters could be used in classification. 
BAUKE (I) was among the first to urge this latter idea when, in 
an effort to determine the position of the Cyatheaceae, he searched 
the gametophyte for decisive characters to add to those afforded by 
the sporophyte. The examination of the prothallium of this family 
convinced him that aid could be gained there, and he extended his 
observations to the Schizaeaceae and meant to take up other 
families. Before this work was completed, however, he died. 
About ten years after this, GorBEL (9) followed a study of the 
prothallia of a number of epiphytic ferns with a discussion of the light 
thrown by them on the possible origin of ferns from algae through 
bryophytes. In his later work (11) he adds to his account of different 
gametophytes and reviews his former conclusions, ending with the 
statement that “within the single natural groups also one may well 
recognize a conformity in the formation of the prothallus which is 
expressed in the possibility of arrranging them in series.” From his 
investigations in 1896 Herm (12) came to similar conclusions as 
to the value of gametophytic characters. 
It certainly seems worth while to review the situation and see 
whether something may not be added from this side to the points 
already made by the study of the sporangial and vascular develop- 
ment of the sporophyte. Any such attempt, however, must be pre 
ceded by considerable work in two directions: (1) although the 
Botanical Gazette, vol. 49] [168 
