CRYPTOGAMS 339 
a mass of spores, mingled with elongated filaments called 
elators, which, by their elastic movements, assist in dissem- 
inating the spores. These latter, on germinating, produce, 
not a simple sporophyte like that which bore them, but 
the thallus of the liverwort with all its complicated arrange- 
ment of antheridia and archegonia and vegetative organs 
that seem to foreshadow, by the analogies they suggest, 
the coming of the higher plants. 
394. Sexual and asexual reproduction. — We find here 
a very marked change from the simple reproductive processes 
observed in the alge and fungi. In the forms thus far con- 
sidered, this function was carried on mainly by simple vege- 
tative fission or budding, with a more or less irregular in- 
tervention of resting spores. If only one kind of spore is 
concerned, reproduction is said to be asexual. When two 
different kinds of cells, the egg and sperm cell, unite to form 
an odspore, as in the liverworts, reproduction is said to be 
sexual. While sexual reproduction takes place to some 
extent among both alge and fungi, the prevailing method 
among thallophytes is asexual, and may be carried on in 
three different ways: by fission (and budding), by resting 
spores, and by conjugation. 
Representing the plant body by A and the resting spores 
by a, the primitive asexual processes may be expressed to 
the eye by the accompanying formulas : — 
(1) Fission and budding: A-~A—-+A—-A—> 
(2) Resting spores: Aa—Aa—->Aa—> 
(3) Conjugation: A +A—-a->A+A—->a—> 
In (3), as was seen in the conjugating cells of the spirogyra 
(342), the method is a little more complicated, showing an 
approach toward the sexual process. In each of these cases, 
however, there is only one kind of cell concerned, while in 
the liverworts there are not only different kinds, techni- 
cally known as gametes, but specialized organs, archegonia 
and antheridia, for producing them. The thallus body 
bearing these organs is termed the gametophyte, because it. 
