1900] CURRENT LITERATURE 
445 
Microlepia}, Lindsayez, Pteridez, and other Polypodiacee, together with 
Woodsia, Hypoderris, and Deparia. 
It is noted with interest and approbation that the terms Eusporangiatae 
and Leptosporangiatae are dropped as designating systematic divisions, but 
retained as descriptive words. The difference in the mode of origin implied 
by these terms is regarded as marking no important biological feature, 
whereas the distinction between the three groups proposed rests upon facts 
of far-reaching biological significance, and conveys in each case a definite 
morphological conception. 
In the Szmp/ices the sporangia are of simultaneous origin, upon a recep- 
tacle which may be slightly sunken, flat, or slightly projecting; also, they 
are of relatively large size, sessile, and usually produce a large output of 
spores (ranging from 128 to over 7000). The annulus when present is oblique, 
and dehiscence is in a median plane, correlated with freedom for lateral 
spreading. The protective arrangements are usually absent or inefficient, 
and the whole group is to be regarded as displaying primitive characters. 
In the Gradatae the sporangia are borne in basipetal succession, with 
regular orientation, upon a more or less elongated receptacle; also they are 
usually of smaller size, sessile or with short stalks, and the output of spores 
is typically sixty-four or lower. The dehiscence is lateral and oblique; and 
the annulus is oblique, correlated with freedom only in a direction obliquely 
upwards. In general the indusium is present as a basal cup or basal flaps. 
In the M/ix¢ae the sporangia are of various ages intermixed, without regu- 
lar orientation, upon a sunken, flat, or slightly projecting receptacle ; also 
they are relatively small, with more or less elongated and thin stalks, and 
the output of spores is sixty-four or under. The annulus is vertical, and the 
dehiscence transverse, correlated with freedom directly upwards, The pro- 
the evolution of the sporophyte in homosporous Filicales. 
gest a single line of descent, but rather parallel development, the members 
of each of the three divisions not necessarily being of common descent, but 
grouped according to common adaptation, just as are the sced-plant. 
It would be profitable to consider the summaries of peat 
under each group ; also the morphological discussion of the sorus, rt 4 st 
the indusium, the receptacle, and the sporangium with its stalk, annu as 
output of spores; and also the discussion of the biology of i a Sa 
includes the production and nutrition of spores, their proce bes ng fi 
and their dispersion; but for all these interesting topics the origina! pap 
Must be consulted.— J. M. C. 
Mr. W. A. CANNON has published 
of the flower and embryo of Avena fatua, 
the results of a morphological study 
the wild oat (Proc. Calif. Acad. 
