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 Pzlobolus, commonly called 
Squirting Fungus on account of the way it throws its sporangia. 
B 
Fig. 313. — Bread Mold, Rhizopus nigricans. A, piece of bread on which 
there is a growth of Mold (x 4). 3B, plant body of Bread Mold, showing 
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 aérial, 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 zodspores, conidia, and aérial spores. 
