362 



THALLOPHYTES 



there is abundant conjugation and formation of zygospores. In 

 many laboratories the spores of both strains are kept in stock, 

 and conjugation is obtained whenever desired by using spores 

 of both strains in growing the cultures. 



Another Mold of this order is Pilobolus, commonly called 

 Squirting Fungus on account of the way it throws its sporangia. 



Fig. 313. — Bread Mold, Rhizopus nigricans. A, piece of bread on which 

 there is a growth of Mold (X 3). B, plant body of Bread Mold, shoT\'ing 

 the hyphae (r) which penetrate the bread, the hyphae which grow up and bear 

 the sporangia (s), and the hyphae (a) (stolons) which grow prostrate on the 

 surface of the substratum and start new plants. (X about 20.) 



It is common on stable manure and resembles Bread Mold. The 

 hyphae become turgid and swollen just beneath the sporangia 

 and finally burst, hurling the sporangia with considerable force, 

 whence the name Squirting Fungus. 



In the True Molds, where there are no swimming spores, the 

 Phycomycetes become entirely aerial, although the coenocytic 

 plant body and conjugation still suggest a relationship with the 

 Green Algae. The mycelium, a tangle of hyphae with no definite 

 shape in Phycomycetes, shows some differentiation into absorbing, 

 vegetative, and reproductive structures. The chief propagative 

 structures of the group are zoospores, conidia, and aerial spores. 



