THE EVOLUTION OF THE SEX ORGANS OF PLANTS. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
- 
FLORENCE LYON. 
(WITH SIXTEEN FIGURES) 
Wiruin the last twenty-five years there have been repeated 
attempts to bridge the chasm between the bryophytes and algae, 
but no transitional stages have been found between the unicellu- 
lar sex organs of the green algae and the multicellular arche- 
gonium and antheridium of the bryophytes. 
Morphologists have persistently fixed their attention upon 
the Chlorophyceae in their search for ancestral conditions, and 
have regarded the brown and red sea-forms as aberrant. Per- 
haps this is because no bryophytes, so far as is known, occur in . 
salt or brackish water, and but few forms of brown algae exist 
in fresh. More likely, the attention focused on the alternation 
of generations, and the suggestion of an antithetic sporophyte 
and gametophyte in Coleochaete, Oedogonium, and Ulothrix, 
have been so dominant that the other groups have been set aside 
as unfruitful fields for investigation. All morphologists of note 
have laid stress upon the development of the sex cells and the 
sex organs as of the greatest importance in determining any 
theory of evolution. While the vegetative part of the gameto- 
phytes of bryophytes and pteridophytes is most changeable, 
appearing in many bizarre forms in the leafy jungermannias and 
the mosses, and varying from thin sheets of cells of the most 
primitive sort to tuberous bodies with highly differentiated tissues 
in the club mosses, simulating those of the higher plants, the sex 
organs of a group retain, as a rule, a constant monotonous type, 
varying from one another in related genera only in unimportant 
details, such as thé length of the neck, the presence or absence 
of a stalk, the total emergence, or the whole or partial submer- 
gence of the archegonium in the vegetative tissues. 
280 [ APRIL 
