624 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
prothallium lias disappeared. The cells of the prothallium are infested 
by an endophytic fungus. 
The author then discusses the comparative structure of the prothallia 
of species of Lycopodium at present known, and dissents from the view 
of Bruchmann * that it should, on this ground, be split up into a 
number of distinct genera. 
Leptosporangiate Ferns.f — In a scientific classification of the 
Filices, Prof. F. 0. Bower advocates the use of characters derived from 
the sporophyte in preference to those derived from the gametophyte. 
The characters regarded as of the greatest importance are : — (1) The 
relative time of appearance of sporanges of the same sorus ; (2) Certain 
details of structure of the sporange, including its stalk; (3) The orien- 
tation of the sporanges relatively to the whole sorus ; (4) The potential 
productiveness of the sporange as estimated by its spore-mother-cells, 
and the actual spore-output. On this basis he classifies the homospor- 
ous ferns as follows : — 
Simplices 
Gradatae 
Mixtae 
( Marattiaceae 
Osmundaceae 
Schizaeaceae 
Gleicheniaceae 
Matonineae 
' Loxsomaceae 
Hymenophyllaceae 
Cyatheaceae 
Dicksonieae 
Dennstaedtiinae 
The bulk of the 
Polypodiaceae 
Eusporangiate 
Leptosporangiate 
The Simplices have all the sporanges of the sorus formed simultane- 
ously ; the Gradatae have them disposed in basipetal succession ; the 
Mixtae have sporanges of different ages intermixed. The Simplices 
and Gradatae have^ an oblique annulus (where definitely present) ; the 
Mixtae (with very few exceptions) have a vertical annulus. None of 
the Mixtae have a higher spore-output pei^ sporange than 64 ; but this 
number is exceeded by some of the Gradatae, and large numbers are 
the rule in the Simplices ( Hymenophyllum turibridgense may have over 
400). The Simplices and Gradatae have relatively short thick stalks ; 
the Mixtae have usually long and slender stalks. The orientation of 
the sporange in the Simplices and Gradatae is usually definite ; in the 
Mixtae it is indefinite. The receptacle is often elongated in the Gradatae, 
but not in the Simplices or Mixtae. It is claimed that a biological 
advantage would be gained by the suggested transitions. 
The proposed basis would not bring about any great change in the 
current classification of Leptosporangiate Filices. If the suborders 
Osmundaceae, Schizaeaceae, and Marattiaceae are transferred from the 
end to the beginning, we have the Simplices. The Gradatae include 
the Cyatheaceae, Dicksonieae (excluding Dennstoedtia ), Hymenophyl- 
laceae, and Loxsomaceae. 
* Cf. this Journal, ante , p. 302. 
t Proc. Koy. Soc., lxv. (1899) pp. 96-9 ; Ann. of Bot., xiii. (1899) pp. 320-4. 
