190 



CRYPTOGAMS 



451. This process differs from oospore formation in 

 Vaucheria chiefly in the usual presence of several egg 



cells in each oogonium, and in the con- 

 duction of the fertilizing cells (or nuclei) 

 to the egg cells by means of tubes. In 

 Vaucheria, it will be remembered, the 

 fertilizing cells are an- 

 therozoids. Frequently 



309. Fertilizatiou of • xtt , ivr u ^i 



Water Mold: "^ ^^^^cr Molds there 



a, antheridiai is this further peculiar- 

 ity, that without fertili- 

 zation egg cells become oospores capable 

 of germination. 



452. It is from resting oospores in the 

 dead leaves that the plant is obtained 

 for study, as recommended above. The 

 oospores on germinating shortly give rise to zoospores 

 (Fig. 310), and these infect the dead flies, etc., thrown 

 into the water. 



310, Germination of 

 the oospore : 

 a, zoosporan- 

 gium ; s, zoo- 

 spores. 

 — De Bary. 



Sac Fungi (Ascomycetes) 



453. The name Sac Fungi or Ascomycetes (asciis^ 

 sac, and mycetes^ fungi) is given from the fact that 

 spores are borne in more or less oval, club-shaped, or 

 elongated sacs at the ends of hyphse (Fig. 313). The 

 sacs may be present in large numbers and are generally 

 grouped in special structures, or " fructifications," built 

 up from the mycelium around the sac-bearing hyphye. 

 The following common forms will serve to familiarize the 

 student with prevailing types of fructification, for it is 

 by the forms of these structures that the different Sac 

 Fungi are chiefly distinguished. 



454. Peziza. — Common species of Peziza are most readily 

 found growing on rotting logs and sticks, though many 

 spring from the soil. The mycelium of septate threads 

 spreads through the substratum for absorption of decaying 

 organic matter. The fructification, known as apothecium^ 

 is in many species saucer-shaped (Fig. 311), in others 



