190 



CnrPTOGAMS 



451. This process differs from oospore formation in 

 Vaueheria chietiy in the usual presence of several egg 



cells in eacii oogonium, and in the con- 

 duction of the fertilizing cells (or nuclei) 

 to the egg cells by means of tubes. In 

 Vaueheria, it will be remembered, the 

 fertilizing cells are an- 

 therozoids. Frec;[uently 

 in Water Molds there 

 is this further peculiar- 

 ity, that icIfJioKf fertili- 

 zation egg cells become oospores capable 

 of germination. 



452. It is from resting 0(ispores in the 

 dead leaves that the plant is obtained 

 for study, as recommended above. The 

 0(")spores on gernnnating shortlj' give rise to zoospores 

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

 into the water. 



.S09. Fertilizatiun o£ 

 Water Jl.ild: 

 a, antheridial 

 tube. 



310. Germination of 

 the oospore : 

 «, zodsporan- 

 gium ; 5. zoo- 

 spores. 

 — De Bary. 



Sac Fungi (Ascomycetes) 



453. The name Sac Fungi or Ascomycetes (^aseus, 

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

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

 elongated sacs at tlie ends of hyplne (Fig. 313). The 

 sacs may be present in large numbers and are generally 

 grouped in special structures, or " fi'uctifieations,"" built 

 up from the mycelium around the sac-bearing hyplue. 

 The following commim forms will serve to familiarize the 

 student with prevailing types of fructification, for it is 

 b}' the forms of these structures that the different Sao 

 Fungi are chief!)- distinguished. 



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

 found growing on rotting lugs and sticks, though many 

 spring from the soil. The m3'celium of septate threads 

 spreads through the substratum for al)sorption of decaying 

 organic matter. The fructification, known as apothecium, 

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



