THE THALLOPHYTES 345 
opposite. ‘The result of the process is a new cell called a zygospore 
or zygote. ‘This method is called scalariform conjugation. The 
zygospore forms a thick cell wall about itself. It is set free by 
decay of the walls of the old cell and falls to the bottom of the 
Fic. 250.—Vaucheria sessilis. A, Terminal portion of a filament showing the 
appearance of a partition wall separating the newly formed sporangium from the 
rest of the filament. B, Same, after escape of zodspore (<). C, A portion of 
the margin of the zodspore. D, Young plant developed from a zoéspore with 
rhizoids (r). (From Strasburger, Noll, Schenk and Schimper; A, B, &, after Gotz; D, 
after Sachs from Altmann’s Alga; C, after Strasburger.) 
water, there to undergo a resting stage until favorable conditions 
for growth arise. 
Professor F. E. Lloyd has shown that in Spirogyra longata, con- 
jugation takes place between adjacent cells of the same filament. 
