Notes. 
165 
AN ALGA-LIKE EERN-PROTH ALLIUM. — T he Fern-pro- 
thallium, which forms the subject of this note, is so remarkable in 
character, and presents features of such general biological interest, 
that I have thought it desirable to offer a preliminary account. 
The prothallium belongs to Schizaea bifida , a Fern confined to New 
Zealand and certain parts of Australia \ 
The prothallium is quite unlike the ordinary types of Fern-prothallia, 
and is strongly suggestive of an Alga. A good specimen has the 
form of a soft-looking round green cushion, from a quarter of an inch 
to half in diameter. Erect green filaments can be seen projecting 
above the general surface even with the naked eye. 
Closer examination shows that it is composed of branched filaments. 
Each filament is a single row of cells, the cells being rather large, about 
• 25 mm. in length and a third or fourth of this in thickness, but may 
be longer where less illuminated towards the centre of the prothallium. 
Some of the filaments lie on the surface of the ground, and from 
these erect filaments are given off which usually branch abundantly, 
and may rise to the height of 3 and 4 mm. 
The development of the branches can be readily followed. Each 
filament has an apical cell, from which segments are cut off behind ; 
these segments do not divide again, though any one may bud out 
laterally at its upper end to form a branch which repeats the features 
of the parent filament. Each segment commonly gives rise to but 
one branch, but at the centre of the prothallium branching may be 
more crowded. Not all the segments give rise to branches; the last 
branch formed may be several cells behind the apex of the parent 
filament. A few filaments spread through the underlying soil, and 
these are colourless, but otherwise of similar character, except that 
they bear at intervals distended, bladder-like cells, which carry short, 
brown root-hairs, usually two to each of the distended cells. 
Filamentous prothallia are already known in Trichomanes, and, as is 
well known, small more or less filamentous prothallia occur in many 
Ferns when spores are sown too quickly. But these starved fila- 
mentous prothallia bear male organs only. 
The prothallia of Trichomanes are incompletely filamentous, for 
although the antheridia are borne by the filaments, the archegonia 
1 The filamentous prothallium of another species of the genus is already known ; 
see Elizabeth G. Britton and Alexandrina Taylor, Life History of Schizaea pusilla. 
Bull. Torrey Bot. Club, New York, vol. xxviii, 1901. 
