THE ANTHEROZOIDS IN ASTERELLA CALIFORNICA 381 
tively colorless tissue in which the antheridia are imbedded which 
furnishes much of the force by which the antherozoids are ejected. ° 
The mechanism effecting the ejaculation of the antherozoids 
consists of two parts —/irst, of the shiny, water-absorbing matrix 
consisting of gelatinized mother-cells and thin walls, in which the 
antherozoids lie and which fills and distends the ripe antheridium 
still enclosed by the single layer of peripheral cells ; second, the 
thin-walled, large-celled, water-absorbing tissue composing the 
cushion, in chambers of which the antheridia develop. These 
two, the tissue and the slime, expand in opposite directions as 
they absorb water, the one tending to decrease, the other to in- 
Fic. 4. Section through cushion, parallel to and below surface of thallus, show- 
ing cavities containing antheridia (@ and 4), empty cavities, and cavities nearly obliter- 
ated (c and @) by pressure of the thin-walled cells composing cushion, >< 22. 
Fic. 5. Enlarged drawing of a in fig. 4, 172. 
Fic. 6. Section through antheridium at right angles to surface of thallus, 172. 
The lettering in figs. 5 and 6 denotes: a, wall of antheridium ; 4, turgid cushion- 
tissue compressing antheridium ; ¢, mass of antherozoids in slime composed of degener- 
ated walls and contents of mother-cells. This absorbs water and distends antheridium ; 
d, solid chlorophyll-containing tissue, with opening of chamber; ¢, water-absorbing 
turgescent cushion-tissue. The figures were drawn with Leitz drawing: prism. 
crease, the size of the chambers containing antheridia. The two 
Pressures would tend to offset each other and would affect 
; Nothing if they met on all sides of the antheridia. The chambers 
in which these lie, however, are open above and are covered by 
the chlorophyll-containing, smaller-celled, and more rigid tissue 
indicated by d@ in jig. 6. Hence the antheridia are distended in 
all directions, upward as well as otherwise, and are compressed 
from all sides, except from above. The distending and compress- 
ing strains finally result, under these considerations, in the rupture 
