THALLOPHYTES FUNGI 287 



There are a great many other types of Agaricacece. Some 

 of them produce shelf-like sporophores with the gills on the 

 under side. They form very conspicuous growths on trees and 

 fallen timber. 



The Hydnacece have tooth-like growths on which the spores 

 are borne; the Polyporacece have pore-like structures on which 

 the spores are borne, and the Thelephoracece have a smooth sur- 

 face on which the spores are borne. 



The Lycoperdacece or puffballs have more or less globular 

 sporophores made up of two well-defined layers or peridiums 

 enclosing great masses of spores. They are very prominent and 

 well-known forms. 



Some of the fleshy fungi are valuable for food, while others 

 are very poisonous. Some of them are very destructive to grow- 

 ing trees and to lumber. The fact that many of the fungi are 

 destructive to other plants, especially to our agricultural crops, 

 makes them one of the most fruitful fields of study. The study 

 of the fungi is known as mycology and may be considered the 

 basis of plant pathology (see page 250). 



LABORATORY EXERCISES. 



Exercise 1. Examine such material of Myxomycetes as may 

 be available. 



Exercise 2. Examine type specimens of bacteria. 



Exercise 3. Rhizopus nigricans. (This fungus can bet readily grown 

 on moist bread under a bell jar.) Note the growth on the bread, especially 

 the upright sporangiophores bearing the sporangia. 



Examine under the microscope and note the delicate hyphae and its 

 method of branching. Note the rnizoids at the base. Note the sporangium 

 and its columella and spores. Examine fruiting material for zygospores. 

 Compare with the algae which you have studied. 



Germinate some of the spores in a hanging drop. See exercise for 

 germinating pollen grains, p. 107. Water can be used instead of 

 sugar solution. 



Exercise 1\.. Saprolegnia sp. (This fungus can be readily grown on dead 

 flies, floated on pond water.) Note the growth of mycelium from the body 

 of the fly. Examine the mycelium under the microscope and note the 

 granular protoplasm, the terminal sporangium and if possible the zoo- 

 spores emerging from a mature sporangium. 



Exercise 5. Albugo Candida. Examine prepared slides ana note the ar- 

 rangement of the conidia and the formation of the oospores. 



Exercise 6. Plasmopara riticola B. & C., the downy mildew of the 

 grape. (This material can be kept dry or preserved in alcohol or for- 



