82 BASIDIOMYCETES 



of the spores ; still others are found in the ovaries of various plants, 

 and occasionally in other parts. A few have light colored spores, 

 among them one affecting the ovaries of Oxalis ; another species 

 is parasitic in the anthers of pinks. The spores thus formed, 

 commonly called chlamydospores, germinate, developing a short 

 promycelium and forming the spores proper which in turn produce 

 the mycelium of the fungus. In the case of the common smuts 

 of cereals the smut spores lie dormant in the furrow of the kernel 

 until the germination of the seeds ; the fungus then germinates 

 producing its spores, whose mycelium penetrates the young plant- 

 let and extends throughout its tissues. As a rule, a parasite of 

 this kind shows little evidence of its presence in the host plant 

 until the spores commence to form, usually in the young ovaries 

 where large quantities of available nutriment are being carried for 

 the supreme effort of flowering and producing seed. This nutri- 

 ment the fungus appropriates and there develops its spores. Two 

 families are distinguished by the method of bearing spores from 

 the germination of the chlamydospores as follows : 



Chlamydospores germinating with a several-celled promycelium which 

 bears the spores at the ends of the cells. (PI. 6. f. 1,2.} 



Family I. Ustilaginaceae. 



Chlamydospores germinating with an undivided promycelium which bears 

 the spores in a cluster at the apex. (P/. 6. f. j. ) 



Family 2. Tilletiaceae. 



Family i. Ustilaginaceae. 



The smuts of this family except those of certain genera cannot 

 be distinguished by their gross appearance or by their microscopic 

 characters from the members of the next family. The biological 

 characters of germination and spore production must be resorted 

 to in order to distinguish them. Some germinate soon after pro- 

 duction, some germinate after a period of rest, and some retain 

 their power of germination for several years but this is somewhat 

 unusual. Their cultivation is a simple matter when conducted in 

 a drop culture in nutrient fluid. The genera are distinguished as 

 follows : 



I. Chlamydospores simple. 2. 



Chlamydospores united in 2'sby a narrow isthmus. SCHI/ONF.LLA. 



Chlamydospores in masses of three or more. 3. 



