Notes . 
3 2 1 
of Ferns need strengthening. In recent years the more detailed 
knowledge of the prothallus has been used for this purpose ; but while 
not denying its value in certain specific cases, the author holds that 
the vegetative development of the prothallus is an uncertain guide to 
a general classification. On the other hand the archegonium is so 
uniform in its character that it gives little help ; the comparison of the 
antheridium is, however, a useful aid, though not sufficiently varied to 
serve in detail 1 . Accordingly the sporophyte must be the main basis. 
Its vegetative organs have lately been largely used for systematic 
purposes by Christ 2 ; but the same objection holds here as in 
Phanerogams to the use of these as characters of first rank for 
comparison. An attempt has therefore been made in this memoir to 
strengthen the characters derived from the sorus by a fresh examina- 
tion of its details, and certain of its features will now be used for 
purposes of general comparison, which have hitherto received too 
little attention ; they are — 
1. The relative time of appearance of sporangia of the same sorus. 
2. Certain details of structure of the sporangium, including its stalk. 
3. The orientation of the sporangia relatively to the whole sorus. 
4. The potential productiveness of the sporangium as estimated by 
its spore-mother-cells, and the actual spore-output. 
Observations of these features extending over all the more important 
living genera, coupled with data of habit and the characters of the 
gametophyte as collateral evidence, have led the author to divide the 
Homosporous Ferns thus : — 
r Marattiaceae Eusporangiate 
Osmundaceae 
Simplices ■< Schizaeaceae 
Gleicheniaceae 
k Matonineae 
Loxsomaceae 
Hymenophyllaceae V Leptosporangiate 
Gradatae^ Cyatheaceae 
Dicksonieae 
< Dennstaedtiinae 
1 Heim, Flora, 1896, p. 355, &c. 
2 Die Farrnkrauter der Erde, Jena, 1897. 
