1904 | GARBER; RICCIOCARPUS NATANS 171 
ciocarpus, as did Leitgeb, intermediate between Riccia and Mar- 
chantia, but with a distinct difference in conception of the 
arrangement of sex organs. He supposed the antheridia to be in 
several small groups and the archegonia to be scattered along the 
furrow with no attempt at grouping. All of his small groups of 
antheridia really belong together in one large group. The arche- 
gonia are also produced in a single region and should be 
regarded as a definite group. 
A series of increasing concentration of sex organs into groups 
in specialized regions of the plant may be traced up to Marchan- 
tiaceae. Beginning with the lowest species of Riccia, sex organs 
are indiscriminately scattered. In Riccia fluitans there occurs a 
regular alternation of single sex organs. Ricciocarpus produces 
first all antheridia in a group and then all archegonia in a similar 
group, but with less apparent specialization of the areas bearing 
them than occurs in Targionia, which has the groups in special 
pits, and Corsinia which bears them on elevations. 
On the other hand, the simple sporophyte, together with the 
feeding tissue derived from the basal cell of the archegonium, 
indicates primitive conditions not far removed from the simple 
sporophyte of Coleochaete. 
Counts of chromosomes gave four for the gametophyte and 
eight for the sporophyte (jigs. 21, 35). Kruch (9) gives 
eight and sixteen for Riella, and the same numbers are given by 
Farmer (5) and others for Pellia. The sporophyte spindle has 
very prominent and beautiful asters, but no centrosomes could 
be distinguished. The asters are identical with those of Pellia 
as described by Farmer (5), Davis (8), and Chamberlain (16), 
but no attempt was made to study their development. 
BIOLOGY. 
For biological data recourse was had to three sources, namely 
(1) the records of past collections, (2) the careful observation 
of various patches during one full season, and (3) experimenta- 
tion in the laboratory. 
The records of collections furnish facts as to dates and local- 
ities of fruiting in former years. With these data and by personal 
observation it was learned that in certain localities Ricciocarpus 
